The life course paradigm refers to a cohesive set of principles, concepts, and methods that guide research on human lives over time and across changing contexts (Elder, 1998; Shanahan and Macmillan, 2008). Instead of examining static outcomes, the life course paradigm is “dynamic” in nature, depicting individual biography in changing and processual terms. The publication of Children of The Great Depression (1974), by Glen H. Elder Jr., marked a watershed in life course sociology, tracing the consequences of family economic crisis during childhood and adolescence for adult education, work, and family outcomes among two adjacent cohorts of youth. In the following decades, numerous empirical studies in sociology have followed Elder's groundbreaking approach to investigate the effects of the “past” on the “future” life outcomes of individuals and their variations across social groups and contexts (Elder, 1974). Building upon these early empirical endeavors, Elder et al. (2003) identified five principles of the life course paradigm. First, according to the principle of life-span development, human development does not end at a certain stage in life but involves fundamental biological, psychological and social changes from birth to death. Importantly, earlier events and developmental states influence subsequent progressions. Second, the principle of time and place recognizes that the individual life course is “embedded and shaped by the historical times and places they experience over their life” (Elder et al., 2003). Third, the principle of timing, or the “life-stage principle”, states that the meaning and consequences of events depend on when they occur in a person's life. Fourth, the principle of linked lives recognizes that human lives are interdependent; the effects of social change on people's lives depend on their network of interpersonal relationships. Fifth, the principle of agency highlights the active roles individuals play in constructing their own life courses through their actions, reactions, and choices. Furthermore, the multidimensionality of lives, including parallel and interdependent trajectories in work, family, and health, is occasionally highlighted as an additional sixth principle (Fasang and Mayer, 2020).

While these general “paradigmatic principles” from Elder and colleagues have been indispensable in establishing life course sociology, Bernardi et al. (2019) have built on this early theoretical foundation to propose a “life course cube” that offers a more integrated view of life courses processes. As a synthetic representation of the life course, the cube has three axes referencing “three dimensions of time, life domains, and levels at which developmental, behavioral and social process occur” (Bernardi et al., 2019, p. 2). The time axis features the interdependence of historical, present, and future life course processes. The life domains axis recognizes that individual goals, resources, and behaviors are interrelated across domains, including elements of the work-family interplay at the core of the current review. The multilevel interdependence of the life course connects individual action and behavior with the life courses of other people (“individual action level”), the external social structure (“supra-individual level”), and internal dispositions and psycho-physiological functioning (“inner-individual level”). The crossing of the cube's axes pinpoints crucial nodes of interaction within an overall structure of life course interdependence.

Empirically, the life course can be conceptualized as the “age-graded sequences of roles, opportunities, constraints, and events that shape the biography from birth to death” (Shanahan and Macmillan, 2008). The time axis, whether defined by historical context, birth cohort, or individual age, is central to modeling the age-graded life course. Social pathways, the “trajectories of education and work, family and residences that are followed by individuals and groups through society” (Elder et al., 2003), define how individual lives are socially organized and structured by historically situated forces and social institutions. For example, paid work and career pathways, institutionalized in the middle of the 20th century for middle-class white-collar and unionized blue-collar men in the U.S., provided a template for age-graded labor market entry and exit and advancement through internal career ladders; these are no longer available to most contemporary workers (Moen, 2016a). Trajectories, or sequences of roles and experiences, are themselves made up of transitions or changes in state or role. Role entry and exit mark each transition, which is embedded in a trajectory that gives it specific form and meaning. The trajectory can be charted temporally by linking institutionally defined role transitions with a defined sequence, duration, and order. The meaning of a transition depends on its place in a trajectory, consistent with the life-stage principle of timing. Some transitions, called “turning points”, have the potential to produce dramatic change in both the internal and external aspects of the life course (Shanahan and Macmillan, 2008). The degree to which trajectories and transitions “correspond or deviate from social expectations” may be “consequential for life chances” (Macmillan and Eliason, 2003). A large body of research investigates the timing and order of transitions, or the sequencing of social roles, in work and family. Questions often address subgroup variations in the determinants and consequences of these transitions or trajectories within or across life domains, as these contribute to the understanding of stratification and inequality (Shanahan, 2000; George, 2003).

Along with the emergence of high-quality longitudinal panel data that trace respondents over time, statistical models have been developed to capture the variation and complexity of the individual life course. These methods can be generally categorized as event-based or holistic (Billari, 2005). Event-based approaches focus on the timing and/or occurrence of particular events or transitions (for example, transition from school to work or transition to parenthood) and their causes or correlates. Event history analysis examines how covariates of interest influence individuals' probability (“risk” or “hazard”) of experiencing certain events or transitions (Wu, 2003; Allison, 2014; Mikolai and Amos, 2020), such as marriage, parenthood, or divorce in the family domain, and obtaining a first job, job displacement or unemployment, and retirement in the domain of paid work.

A more holistic approach develops algorithms to describe the totality of trajectories, especially in the form of sequences of transitions in either single or across multiple domains (Pollock, 2007; Mayer, 2009; Gauthier et al., 2010). Statistical models developed in recent decades adopt this holistic approach in modeling age-sequenced trajectories of individual attributes, statuses, or roles (usually measured as categorical outcomes). These include optimal matching analysis (or sequence analysis, Abbott, 1995; Ritschard, 2021; for a recent review see Liao et al., 2022), and finite-mixture models such as latent class analysis (LCA) and group-based trajectory models (GBTMs) (George, 2009; Nagin, 2014). The main goals of these trajectory-based models are first, to identify a finite number of discrete trajectories in a population to arrive at typologies of the life course; second, to assign individuals to a specific trajectory group; and third, to relate the trajectory group assignment to individual characteristics or outcomes. A recent methodological advance proposes the combination of sequence analysis and event history analysis to better understand the effects of time-varying covariates on the transition from a state to ideal-typical trajectories (Studer et al., 2018). As for continuous outcomes like wage or occupational prestige, growth curve models appear to be useful tools for modeling change and volatility (George, 2009; Mayer, 2009).

The choice of analytic models depends on the measurement of the variables of interest in different life domains. Work life variables can be metric (e.g., occupational prestige or earnings) or categorical (e.g., employment, unemployment, or out of the labor force). Family trajectories are usually represented as sequences of categorical states (e.g., single, married, divorced, remarried). While much research relies on quantitative measures, life course researchers have demonstrated the value of qualitative methods, or mixed approaches including both qualitative and quantitative data, for in-depth understanding of life course trajectories (Damaske, 2013; Le Roux et al., 2023).

Sociologists' interest in the sources and extent of inequality motivates their attempts to describe and explain how people are allocated to unequal positions in the stratification system, mainly through the paid labor market. The social mobility of individuals is traced both across and within generations (Kalleberg and Mouw, 2018). Intergenerational mobility, measured as the resemblance of “origin” status (parents) and “destination” status (adult children), attracts more attention from mobility scholars, due to its centrality to the understanding of (in)equality of opportunity or openness of the class structure. By contrast, intragenerational mobility refers to “changes in individuals' economic positions or occupational standing over their working lives” (Kalleberg and Mouw, 2018). Though it receives less scholarly attention than intergenerational mobility, intragenerational mobility is of considerable importance in understanding inequality processes across the life course (Cheng, 2014; Jarvis and Song, 2017).

Intragenerational career mobility refers to transitions among jobs and occupations, or changes in earnings and other quantifiable job rewards through the individual career (Kalleberg and Mouw, 2018). Variation in intragenerational mobility is due to individual attributes (both ascribed and achieved characteristics) and structural factors at both meso-institutional (i.e., organizations, firms, industries) and macro-societal levels (i.e., state interventions). As for individual attributes, economic theories are often cited to explain divergent patterns of intragenerational mobility, such as the human capital model (Mincer, 1957; Becker, 1964) and theories of discrimination (Becker, 1957; Cain, 1986). Focusing on the supply-side of the labor market, human capital theory argues that individuals invest in themselves through education, experience, or various forms of training to increase their productive capacities, fostering occupational and wage attainments in the long run (Goldthorpe, 2014). To a certain extent, the economists' assumption of individuals as rational actors who make informed choices about their human capital investment resonates with life course scholars' emphasis on agentic power. However, external factors like discrimination against racial minorities and women in education and the labor market prevent the full exercise of human agency, diminishing the return to human capital. Arguments stressing the demand-side of the labor market emphasize the role of structural forces in career mobility, stemming from firms/organizations, occupations, industries, and macro-societal economic contexts. The internal labor market within firms is key to the structural side of the story (Rosenfeld, 1992).

With the increasing availability of panel data collected over long periods of time, researchers have become increasingly innovative in constructing measures of key dimensions of intragenerational mobility, including transitions, sequences, durations, and trajectories. Some model mobility trajectories of continuous job rewards like wage or income (Cheng, 2014, 2021) or occupational prestige (Lersch et al., 2020). Others emphasize trajectories of career mobility by depicting sequences of categorical outcomes of work like employment status (Muñoz-Bullón and Malo, 2003; Manzoni et al., 2014; Vuolo et al., 2014; Weisshaar and Cabello-Hutt, 2020; Van Winkle and Fasang, 2021). Transitions in the career are depicted by event history analysis, such as entry into the labor market from school (Kerckhoff, 2000; Becker and Blossfeld, 2017), or transitions into and out of employment (DiPrete, 1981; Mont'Alvao and Ribeiro, 2020) and low-wage precarious jobs (Schultz, 2019).

As shown in many studies documenting divergent career mobility trajectories for men and women, women face cumulative disadvantages. At entry to the labor market and in their growth trajectories of labor market outcomes over time, they have persistently lower wages, earnings, and occupational prestige, and more unstable employment. Important family life events, including union formation, dissolution, and parenthood interrupt women's work and lead to gender divergence in career progression.

The moderation of work careers via gender (dis)advantage could be illustrated in several ways, for example, by considering the age of marriage or the effects of divorce and repartnering on career advancement. Due to space limitations, this review focuses on the “motherhood penalty”, which has attracted considerable scholarly interest in recent decades. Based on the increasing availability of longitudinal survey data and the development of fixed-effects regression models, investigators have reached consensus that on average, mothers earn lower wages than childless women; by contrast, fathers obtain a premium in wages compared to childless men. While the precise magnitude and the mechanisms driving the penalty or premium are not fully agreed upon, several theories have been tested in the empirical literature; these highlight human capital, work effort, job characteristics, employer discrimination, and selection (Gough and Noonan, 2013). Recent studies have focused on heterogeneity in the penalty by age, race, marital status, parity, and socioeconomic status indicated by education and income (Budig and Hodges, 2010; England et al., 2016).

The above literature has well-documented the heterogeneity of the wage penalty associated with motherhood and has investigated the mechanisms underlying this effect. However, most empirical studies follow a rather “static” approach. That is, they typically construct a single measure of parenthood penalty based on a comparison between labor market outcomes like wages earned by mothers and non-mothers at a particular point in time, ignoring the possibility of temporal variation in the effect of parenthood across the life course. Relatively little research has examined the long-term effects of family transitions like entering marriage or parenthood on labor market trajectories over longer periods of time. From a life course perspective, such family life transitions are not one-time events, but major turning points that mark the beginning of a long-term life experience. As a result, the motherhood penalty may unfold gradually over the life course, subsequent to first or later births.

Kahn et al. (2014) interact age decade intervals with the number of children in fixed effects models to predict long-term trajectories of women's labor market participation, occupational status, and hourly wage since childbirth. The authors find that motherhood is “costly” to women's careers, but the effects on all three labor market outcomes attenuate with age. Children reduce women's labor force participation, but this effect is strongest when women are younger, and it is eliminated by the time they reach their 40s and 50s. Mothers also seem to regain ground in terms of occupational status over time. The wage penalty persists across the life course only for women who have three or more children. Doren (2019) demonstrates that the motherhood penalty for highly educated women varies across life stages, as those who postpone their first birth to the late 30s even receive a significant premium, presumably due to distinct human capital accumulation patterns across career stages.

Van Winkle and Fasang (2020) build on the analytic framework developed by Kahn et al. (2014) to assess variation in the motherhood penalty across the life course; they also extend the analysis to fathers, generating race and gender specific estimates. Fitting separate models to six intersectional gender-by-race groups (white, black, and Hispanic), the authors examine the varying effects of having different numbers of children over the life course. They find that only white women with three or more children suffer large and persistent motherhood penalties up to age 40, but black and Hispanic women, regardless of the number of children, experience penalties concentrated in a brief age range of 5–10 years around age 30. Fatherhood premiums, confined to brief periods in early adulthood, are only found among white men. Besides the family impacts on changing point-in-time earnings across the life course, studies have also looked into the divergent accumulation of earnings (or lifetime earnings) following different family life courses. Using register data from Finland, Jalovaara and Fasang (2020) highlight the accumulated earnings premium for Finnish men and women who follow the most normative family lives of stable marriage and parenthood, while mid-life earnings (accumulated from ages 18–39) are lowest for unpartnered mothers and never-partnered childless men.

Looking into couple dynamics, Musick et al. (2020) trace mothers' share of couple earnings in the 10-year window around the first birth using panel data from three industrial societies: the US, Germany, and the UK. The authors find steep declines in the mother's share of couple earnings following the first birth across the three societies. Such decline would likely maintain or even exacerbate motherhood wage disadvantage as couples with children would have less motivation to prioritize mothers' career prospects when making relevant decisions (e.g., decreasing women's hours of work, continuing education or vocational training, geographic mobility in favor of husbands' jobs, etc.). Decreasing women's share of couple earnings persists over several years of follow-up, though declines are smaller in the US due to higher female employment rates and longer work hours.

As it is an important transition, the timing of employment re-entry after childbirth has been another life course research focus in studying the labor market consequences of family life. Aisenbrey et al. (2009) examine the differences in the timing and consequences of employment re-entry after transition to motherhood among women in Germany, Sweden, and the United States. They find that US women have the shortest time-out periods after childbirth, as 75% of them are back at work only 6 months after the birth of a first child. However, consistently across the three countries, time-out periods following childbirth tend to destabilize women's careers and increase their risks of downward occupational mobility even when those periods out of the labor force are short.

Another line of research, also adopting a dynamic life course approach, aims to depict career trajectories following the motherhood transition over a longer time span using clustering models like sequence analysis. Hynes and Clarkberg (2005) apply a group-based trajectory method to examine women's employment trajectories across the period of early parenthood (12 months before and 24 months after childbirth) using data from the NLSY79. The authors find that throughout early parenthood, women exhibit significant movement into and out of the labor force. Factors that predict varying levels of motherhood wage penalty also predict different employment trajectories, with the more advantaged women channeled into the “continuously employed” trajectory. Moreover, the trajectories also differ by parity; overall employment rates are lower around the second birth than the first birth, with more mothers at second birth channeled into trajectories that feature lower attachment to the labor market.

Lu et al. (2017) adopt sequence analysis to chart the employment trajectories of women in the first year following childbirth using data from the SIPP. The authors find that most women who were employed before childbirth show a high degree of labor market continuity, but a notable share of them (24%) took less stable paths featuring frequent transition into and out of the labor force. They further demonstrate that the trajectories vary across racial groups and by nativity; non-white women exhibited greater labor market continuation than white women, and immigrant women with shorter length of U.S. residence were more likely to reduce employment than native born women. Killewald and Zhuo (2019) extend the observation window to cover the first 18 years of maternity and identify five common employment patterns of American mothers: three patterns revolve around a single employment status of either full-time (36%), part-time (13%), or non-employment (21%), while the other two patterns are characterized by 6 (15%) or 11 (14%) years of non-employment, followed by a period of transition back to employment.

While the above studies focus on the unidirectional impact of family events on employment outcomes, and studies by family demographers routinely analyze the reverse effects of work on family, both have overlooked how work and family trajectories are interrelated across longer time windows of the life course. A recent line of research has conceptualized work-family trajectories as interlocked multidimensional life course processes and has examined them jointly.

In the US context, Han and Moen (1999) propose a couple-careers model based on the life course perspective to examine work and family trajectories jointly for men and women. The authors use sequence analysis to identify five distinctive career pathways and find that those featuring “delayed-entry” and intermittent career were followed exclusively by women while men were more likely to follow “orderly” and “fast-track” career pathways. Using a marital stability score constructed from a detailed marital history to capture the family trajectory, the authors then show that women in upwardly mobile career paths are more likely to experience marital instability, but men tend to reap the benefits of both career mobility and stable marriage. Using a qualitative case example to illustrate the negotiation of work and family within couples, one husband acknowledged that his wife “sacrificed her career in favor of [their] being able to live here” (p. 107).

Aisenbrey and Fasang (2017) use sequence analysis to examine how gender inequality in work-family trajectories unfold from early adulthood until middle age in two different welfare state contexts, the US and Germany. The authors demonstrate that patterns of work-family interplay across the life course in the United States are less gendered overall but differ widely by social class. On the upper end of the social ladder, work-family patterns characterized by high occupational prestige are fairly equally accessible for men and women. But this gender equality is only a white privilege that does not extend to black men and women. However, on the lower end, both white and black women are far more likely than men to experience the joint occurrence of single parenthood and unstable low-prestige work careers in the United States. The contrast by social class points to the disparate policy supports at the intersections of gender, class, and race in the United States, where disadvantaged lower-class minority women face cumulative pressure from both the labor market and family.

In the context of Germany, the authors find significant and strong gender effects for all work-family clusters. The combination of a high-prestige career with having a partner and several children is largely inaccessible to women. But the more extensive safety net of the German social security system prevents highly unstable low-prestige work trajectories, precluding the coupling between low-prestige employment and single parenthood in Germany. More recently, Fasang and Aisenbrey (2021) examine intersectional inequalities in work and family life courses by gender and race in the U. S. context. Using data from the NLSY79, the study reveals gendered and racialized constraints for Black women who experience the strongest interdependence between work and family life and instability spillovers between the two life domains.

Davia and Legazpe (2014) depict the joint trajectories of employment and fertility for women in Spain over a 20-year span from age 16–35. Using optimal matching analysis, they identify four patterns: (1) early marriage/non-working mother/high fertility; (2) late marriage/working mother/low fertility; (3) early marriage/working mother/high fertility; and (4) late marriage/low labor force participation/low fertility. The authors then demonstrate that education, as a human capital indicator, predicts trajectories featuring higher attachment to the labor market and low fertility. They find some evidence that those who have more traditional values are found in more traditionally oriented trajectories (i.e., early marriage, low labor force attachment, and high fertility).

Scherger et al. (2016) study the joint trajectories of work and family in cohorts of individuals born in the first half of the 20th century in the UK. They demonstrate that while the majority of men followed a trajectory of marriage and family formation with a relatively continuous career, the family-work trajectories of women varied noticeably from one cohort to the next, including increased labor market participation combined with fewer and shorter breaks from work to care for children.

Van Winkle and Fasang (2021) use data collected across Europe to quantify changing employment and family patterns from ages 18 to 50 and to decompose the variance in work and family lives attributable to cohort and country. The authors find a negligible increase in family complexity and a moderate increase in employment complexity over the life course across cohorts, which is in stark comparison to large and stable cross-national differences in work and family lives across 30 European countries. Their findings reveal polarization in Europe between most Eastern and Southern European countries with stable low family complexity compared to Nordic and some Western European countries with high and increasing family complexity. But their study considers work and family trajectories as parallel life trajectories without modeling the two domains jointly.

Studies conducted in non-Western societies to examine work and family trajectories are relatively scarce. Rindfuss et al. (2010) examine the temporal sequence of important life events in family and employment in Japan and find that the life course sequences of young Japanese men and women are very orderly, in contrast to the macro changes in the economy and population. Even though changes did occur in the family sphere, they feature an orderly postponement of both marriage and employment for both men and women; divorce and non-marital childbirth are rare while increasing. Clark and Yi (2020) find similar family patterns in China: while young adults in China postpone family formation as seen in increasing age at marriage, marriage is still the norm and having a child takes place quite rapidly after marriage. Overall, their analysis suggests more continuity than change in Chinese young adults' life course decisions with respect to family formation. Using comparable survey data across 63 low- and middle-income countries, Pesando et al. (2021) adopt sequence analysis to examine shifting family trajectories during transition to adulthood for women across countries and cohorts, documenting significant differences in life course patterns of sexual intercourse, union, and childbirth by macro-regions yet relative stability across cohorts.