In an era when half of marriages end in divorce, cohabitation has become more commonplace and those who do get married are doing so at an older age. So why do people marry when they do? And why do some couples choose to cohabit? The authors reveal what factors encourage marriage and cohabitation in a contemporary society where the end of adolescence is no longer signaled by entry into the marital home. While some people still choose to marry young, others elect to cohabit with varying degrees of commitment or intentions of eventual marriage. The authors’ controversial findings suggest that family history, religious affiliation, values, projected education, lifetime earnings, and career aspirations all tip the scales in favor of either cohabitation or marriage.