The chapter provides an overview of theoretical development regarding the explanation of sex offending. The theoretical models proposed so far can be classified into three categories based on their assumptions on sex offending. The first group of theories are based on a set of assumptions suggesting that individuals having committed sex offenses present a specific and distinctive predisposition toward the perpetration of such behaviors as opposed to other forms of antisocial and criminal behaviors. The second group of theories, the general-criminogenic models, are based on the assumption that the factors responsible for the perpetration of sex offenses are no different than those responsible for the perpetration of antisocial and criminal behaviors. Finally, general-specific models are more integrative in nature and suggest that sex offending perpetration is best explained by the combination of criminogenic factors and factors specific to sex offending. It is argued that theoretical models of sex offending have been limited to sexual violence and abuse and therefore have provided an incomplete view of the multidimensional aspect of sex offending. Future research needs are outlined.