As with social mobility, educational homogamy refers to the degree of societal openness. High social mobility indicates low educational homogamy: class and educational structures are open because people overcome relatively easily class and educational differences. Low social mobility goes hand in hand with high educational homogamy: class and educational structures are closed, and class and educational barriers at the level of everyday practice are more difficult to overcome. This relationship between social mobility and educational homogamy was many times mentioned in social stratification research but it has not been rigorously tested empirically. The article tackles two questions: (1) Is there a relationship between social mobility and educational homogamy in European countries? (2) Is there a relationship between educational mobility and educational homogamy in European countries? To answer the first question we use data from Social Stratification in Eastern Europe after 1989 for six countries. To answer the second question, we use the data from two waves of the European Social Survey (2002, 2004) on forty five countries. Log-linear and log-multiplicative models are used to test these two hypotheses. The hypotheses are tested from a comparative social stratification point of view.