New Evidence on the Cohabitation Revolution
The late twentieth-century rise of nonmarital cohabitation has long been understood as a transformation driven primarily by young, never-married adults delaying or opting-out of marriage. This interpretation aligns with foundational ideas in much of social science: young people serve as the “engines of social change.” But research by Megan Sweeney, Professor of Sociology at UCLA and Associate Director of the California Center for Population Research (CCPR), and Professor of Sociology and Former Associate Director of CCPR, Patrick Heuveline, suggest that this account is incomplete. Their work demonstrates that cohabitation began increasing earlier among previously married individuals (those who had experienced separation or divorce) than among the never married in the US and many international contexts.
At the center of this research is a methodological reconsideration of how cohabitation has been studied. As Sweeney explains, “we felt like we were looking at cohabitation trends through a dirty window,” reflecting longstanding limitations in how these patterns have been measured. She describes their research as building the “demographic architecture for causal explanation,” ensuring that the patterns under study are clearly and accurately defined before seeking an explanation. A central challenge in the study of cohabitation among the previously married is the difficulty of capturing its timing and prevalence, since much of the existing literature has relied on indirect measures, such as cohabitation preceding remarriage or cohabitation status at the time of the survey, which capture only a subset of cohabiting unions.
In one study, Sweeney and Heuveline, revisit the historical roots of cohabitation in the United States by shifting attention to previously-married individuals (those who experienced separation or divorce). Using data from the 1987–88 National Survey of Families and Households, they adopt a cohort-based approach, tracking individuals from the end of their first marriage and measuring whether they subsequently enter a cohabiting union. This design captures a broader range of cohabitation experiences and avoids restricting analysis to only those who eventually remarry. The findings indicate that cohabitation among separated and divorced individuals increased substantially beginning in the early 1960s. This is approximately a decade earlier than the widely recognized rise among never-married populations and suggests that previously married adults played a more central role in the early diffusion of cohabitation than has been acknowledged.
In a separate comparative analysis, Sweeney and Heuveline analyze data from the Fertility and Family Surveys across six countries, including Canada, Finland, Italy, New Zealand, Poland, and Spain. Employing a parallel methodological framework, the study compares cohabitation among previously married individuals (measured within 5 years of marital dissolution) with that among never-married individuals by age 25. Across all six countries, the results show that cohabitation levels rose earlier among the previously married than among the never married. Even in countries where cohabitation diffused more slowly, such as Italy and Spain, postmarital cohabitation levels substantially exceeded premarital levels in comparable periods. These findings reinforce the conclusion that previously married individuals were early participants in the expansion of cohabitation across national contexts.
As the conversation turned from findings to reflection, Sweeney returned to CCPR’s setting, reflecting on its evolution over the past two decades from a relatively small, close-knit group into a large, collaborative, and vibrant community. She described how bringing together scholars across disciplines has created an environment where ideas are continually developed and refined to foster new and creative lines of inquiry that may not emerge in more siloed spaces. Sweeney noted, “The energy of all the great multidisciplinary research going on around me has really enhanced my own work.” That intellectual vitality is a defining feature of CCPR, emerging from sustained collaboration, creativity, and ongoing exchange.
