The marked increase in premarital cohabitation over the last 50 years in the US is part of a constellation of interrelated changes in family demography along with increased divorce rates, declining rates of marriage, increased age at fi rst marriage, and extramarital childbearing (Bramlett & Mosher, 2002 ; Kreider, 2005). The children who experienced the surge in divorces among their parents were more likely to cohabit with a romantic partner when they became young adults (Sassler, Cunningham, & Lichter, 2009 ; Thornton, 1991 ). As the proportion of unmarried partners living together increased, so has the proportion of children who are born to and live with unmarried partners (Bumpass & Lu, 2000 ; Kennedy & Bumpass, 2008 ). In turn, children who live with a cohabiting parent may be more likely to cohabit when they become young adults (Sassler et al., 2009 ). Thus, in just a few generations, cohabitation has become integral to contemporary romantic relationships.