BACKGROUND Studies explaining why cohabiters are more likely to keep money separate than spouses have mainly focused on selection processes, without taking into account the heterogeneity within both union types in levels of commitment. Cross-national studies are rare and have predominantly included Northern and Western European countries, the United States, and Canada. OBJECTIVE This study explains the higher likelihood of cohabiters to keep income separate by selection as well as commitment factors and explores country differences, including countries from Central and Eastern Europe. METHODS Using data from the Generations and Gender Surveys of Bulgaria, France, Georgia, Germany, Romania, and Russia, N=41,456 cohabiting and married individuals are studied. Binary logistic regression models of the likelihood that respondents keep money separate are calculated. RESULTS Across countries, higher education, female labor market participation, both partners being employed, short union duration, absence of joint children, presence of separation thoughts, and (for cohabiters) a lack of marital intentions are the most persistent correlates of keeping money separate. Differences between cohabiters and married couples are reduced when selection and commitment are taken into account, but are still significant. Cross-national variation in the effect of cohabitation on keeping separate purses is persistent. CONCLUSION Different money management strategies of cohabiters and spouses can be explained to some extent by selection processes and inherent differences in the level of commitment within cohabitation and marriage. Countries also differ in the socio-economic context and norms concerning the way intimate relationships are organized which might lead to persistent differences in the way cohabiting and married couples organize their income.