This thesis empirically examined the validity of Wortley and Smallbone’s (2006) offender x situation interaction typology of sexual offending, using a sample of male adolescent sexual offenders. Driven primarily by applied concerns with the situational prevention of sexual offending, this typology draws on the ideas that have emerged from interactional psychology to emphasise the interdependent influence of internal (dispositional) and external (situational) factors on sexual offending. It proposes the existence of three sexual offender types (‘Predatory’, ‘Opportunist’, and ‘Situational’), distinguished based on the strength of their predisposition towards sexual offending, and three offence situation types (‘Challenged’, ‘Tempted’, and ‘Precipitated’), that vary in the extent to which they allow/encourage sexual offending. It highlights that those with stronger predispositions towards sexual offending will do so across a wider range of situations, including those that inhibit/discourage such behaviour, while those with weaker or ambivalent motivations will limit their sexual offending to situations that are perceived to encourage such behaviour, or make it easy and safe to engage in.