This chapter explores the neurobiological bases of sexual function and the subsequent development of maladaptive reproductive behaviors. The chapter begins by discussing normal sexual development before describing several genetic conditions that can disrupt such development (e.g., Turner’s syndrome). The chapter then details the fundamental components of adaptive sexual arousal, including cognitive, autonomic, endocrine, motivational, emotional, and inhibitory processes. It then addresses various conditions affecting normal sexual function, such as hypoactive sexual arousal, erectile dysfunction, and dyspareunia. A significant portion of the chapter is dedicated to highly maladaptive behaviors, including compulsive sexual behavior, paraphilic disorders, and sexual aggression. For each condition, the chapter discusses proposed underlying neurobiological mechanisms accounting for dysregulated sexual behaviors.