Book excerpt: This book brings together historical, social science, and legal considerations to examine the role that procreative and child welfare claims have played in policy and legal debates involving same-sex marriage. In doing so, the book addresses and refutes the claim that same-sex marriage bans are needed in order to promote responsible procreation and child welfare objectives. It places the current marriage debates in a broader historical context by exploring how the procreative and child welfare claims that are today used to try to deny same-sex couples the opportunity to marry are similar to earlier arguments used to defend interracial marriage bans, laws prohibiting disabled individuals from marrying, and the differential treatment of children born out of wedlock. The book also examines the social science literature on the relationship between family structure and child well-being and assesses its relevance to the policy and legal debates over same-sex marriage. In particular, the book explores the relevance of the social science studies on the children of lesbians and gay men to the constitutional question of whether same-sex couples have a right to marry. The book looks closely at the gay marriage cases that recently reached the Supreme Court and explains why the constitutionality of same-sex marriage bans cannot be defended on the basis that maintaining marriage as an exclusively heterosexual institution helps to promote the best interests of children.