This article examines the association between cohabiting partners’ educational homogamy and transition to marriage. This paper enriches previous studies with its comparative dimension to find out if and how the association differs in countries with different meanings of cohabitation – in Austria, Poland, and the Czech Republic. It also examines if and how the association between the transition to marriage and educational homogamy is changing over time. Using data from the first wave of the Generations and Gender Survey (GGS), the analysis shows that the transition to marriage depends on partners’ relative education only in countries where cohabitation and marriage are two very different institutions – Poland and the Czech Republic. Educational hypergamy and hypogamy are not associated with the transition in the same way. In cohabitations where the man is more educated, the probability of marriage is half that compared to homogamous cohabitations, whereas cohabitations with a more educated woman are not significantly different from homogamous cohabitations. Over time, the association between relative education and the transition to marriage has not changed.