This paper will explore the role of Offence Paralleling Behaviours (OPB) in relation to risk assessment and risk reduction in sexual offenders. Specifically, the paper addresses the difficulty of identifying OPBs in relation to sexual arousal and sexual interests due to the increased use of detection evasion skills (DES) in this domain. Sexual interest will be defined as the fantasies, thoughts, ideas or preferences that individuals find sexually attractive, and arousal defined as the resulting response. Previous research (Hanson & Bussière, 1998) concluded that sexual deviance was a significant factor in sexual recidivism. Further, meta-analytic reviews (Hanson & Bussière, 1998; Hanson & Morton-Bourgon, 2005) consistently show that deviant sexual interest, (for example sex with children, or to include adult sexual coercion), are the strongest predictors of future offending. Therefore a thorough understanding of current sexual interest is important to assess risk of further offending. However, it can be very difficult for service users to discuss such personal interests. The paper will also consider the importance of a thorough functional analysis of offending behaviour and briefly describe the development of a new tool to assist with the assessment of current sexual interest. Potential treatment pathways in relation to sexual OPBs are discussed, reflecting the complex nature of offence related sexual arousal.