In this chapter, family sociological theories and research on different-sex couples are discussed from the perspective of same-sex couples’ division of work and care before and after (any) transition to parenthood. Our focus is primarily on research from the United States, the Netherlands, and the four bigger Nordic countries of Denmark, Finland, Norway, and Sweden. These were among the first countries to legalise same-sex marriage and parenthood. Theories and previous research indicate that the partners in same-sex couples are less likely than the partners in different-sex couples to specialise in paid and unpaid work, and are more likely to share childcare responsibilities and family leave entitlements. Still, identity formation and gender influence these couples as well, even if these factors are less likely to determine the division of work and care between the partners. In conclusion, we call for more synergies of disciplines and for traditional family sociology to acknowledge the important inroads made by research on same-sex couples.