This study draws upon a sample of men and women from Waves I and IV of Add Health to examine the linkages between the adolescent family environment and cohabitation behavior across the transition to adulthood. Using event history modeling the current paper considers the association between a variety of family factors and both the timing of first cohabiting unions and their outcomes (marriage, break up, still cohabiting). This paper also considers whether the impact of predictors for cohabitation timing and outcomes varies depending on the age of individuals. Results indicate that exposure during adolescence to family instability, parental cohabitation, lower parental SES, and low family belonging were associated with an elevated likelihood of entering into cohabiting unions, but primarily during adolescence and early adulthood. Family factors, including family belonging and parental relationship history, were also associated with the outcomes of first cohabitations.