There has been considerable disagreement among political scientists over the relative merits of political culture versus rational choice explanations of democratic and liberal norms and commitments. However, empirical tests of their relative explanatory power using quantitative evidence have been in short supply. This article employs national probability sample surveys conducted in 1994 to assess differences between Czechs and Slovaks in the expression of democratic norms and liberal attitudes with respect to economic, political, social and ethnic issues. The applicability of an explanation focusing on long-standing cultural differences between the two countries is compared with a rational choice explanation based on national differences in their recent experiences of political and economic transition. It is shown that differences in the expression of support for marketization and democracy in the two countries can be explained relatively parsimoniously in rational choice terms. The explanatory contribution of political culture appears to relate only to a narrow range of attitudes and values.