Since the early 1980s, five assumptions have influenced the assessment, treatment, and community supervision of adolescents who have offended sexually. In particular, interventions with this population have been informed by the assumptions that these youth are (i) deviant, (ii) delinquent, (iii) disordered, (iv) deficit-ridden, and (v) deceitful. There is very little research to support these beliefs, however, and some researchers and clinicians have long pointed out that adolescents who commit sexual crimes are heterogeneous and that there is no typical profile. Indeed, many adolescents who commit sexual crimes display healthy sexual interests, are prosocial in their orientation, are not psychiatrically disordered, can be described by many strengths and protective factors, and are open regarding past sexual crimes and their sexual interests. If the goal of intervention is to help adolescents to prevent future offenses, then it is essential for all involved in their care to be more critical of these erroneous assumptions that have influenced the field for the past several decades.