A number of studies show that premarital cohabitation is associated with an increased risk of subsequent marital dissolution. Some argue that this is a consequence of selection effects and that once these are controlled for premarital cohabitation has no effect on dissolution. We examine the effect of premarital cohabitation on subsequent marital dissolution by using rich retrospective life-history data from Austria. We model union formation and dissolution jointly to control for unobserved selectivity of cohabiters and non-cohabiters. Our results show that those who cohabit prior to marriage have a higher risk of marital dissolution. However, once observed and unobserved characteristics are controlled for, the risks of marital dissolution for those who cohabit prior to marriage are significantly lower than for those who marry directly. The finding that premarital cohabitation decreases the risk of marital separation provides support for the "trial marriage" theory.