Lesbian and gay couples by definition cannot establish sex-specific divisions of domestic tasks, at least not literally. Previous research has shown that high levels of equality characterize domestic work arrangements in same-sex couples. This study scrutinizes explanations for this. The theoretical background stems from family economics, from the theory of relative resources and from gender role and life-course considerations. The empirical analysis is based upon the Generations and Gender Survey from Austria, Belgium, France, the Netherlands, Norway, Sweden and Australia. Results show that same-sex partners engage in more tasks equally, that their housework-sharing pattern is less segregated and that the partners' workload is more equally balanced. Comparative advantages, life-course differences and gender roles contribute to the explanation of higher levels of equality in same-sex compared to different-sex relationships.