The 25 chapters in this second edition of the Handbook of Neurosociology represent the breadth and depth of advances in research and theory in the last decade. This impressive body of work makes it clear that sociological understanding of human emotion, social interaction, social problems, and cultural variation cannot be considered complete without a foundation that includes insights from neurosociology. Nonetheless, neurosociology remains a marginal topic in sociology, as reflected in it having the smallest of the American Sociological Association’s 53 sections and a meager fraction of the articles published in sociology’s peer reviewed journals. This introductory chapter first identifies the basis of this disinterest by reviewing the history of the disciplinary divorce between sociology and evolutionary biology; it then identifies the more recent developments that have removed the grounds for divorce and describs the new directions represented in this book.