This chapter introduces the concept of parentalization, defined as the ability to become parents and be recognized as such, both legally and via social policies. Applying the concept to same-sex couples, we examine how states may facilitate or hinder the transition to parenthood through laws and policies in five Northern European countries; Denmark, Finland, Norway, Sweden, and the Netherlands. Trends in the number of children zero years of age in married/cohabiting same-sex couples suggest a link between parentalization and realized parenthood. As partly indicated by these trends, parentalization is a gendered concept, and parenthood is more readily available to some couples than to others. Perhaps most importantly, very few same-sex couples have been able to jointly adopt a child. The fact that married female couples face fewer barriers to parentalization than other non-traditional couples partly reflects dominant norms on gender and motherhood.