The majority of measured characteristics were similar for both juvenile sex offenders and nonsex offenders; however, sex offenders were younger than the nonsex offenders, had fewer substance use disorders, and had lower levels of disinhibition. Sex offenders had been referred to compulsory treatment more often than nonsex offenders. Also, sex offenders reported being sexually abused in their past more often than nonsex offenders. The authors advise that larger samples, including external informants within other settings and the use of adequate control groups is necessary in comparing sex offenders and nonsex offenders. If further research confirms that sex and nonsex offenders are similar regarding the characteristics studied in the current study, the development of specific and distinctive therapeutic interventions for juvenile sex offenders may be questioned. On the other hand, when specific differences can be detected, the extent to which treatment programs should be specific to those differences should be assessed. The sample consisted of incarcerated juvenile male sex offenders (n=30) and juvenile nonsex offenders (n=368). Sociodemographic information was obtained from an official registration system used in all youth detention centers in the Netherlands. Standardized information about childhood adversities was obtained through a structured interview designed by the authors. In order to determine whether a youth had been sexually abused, he was asked whether a family member at least 5 years older had ever touched his genitals or been asked by the older person to touch his/her private areas. Structured interviews also obtained data on the psychiatric disorders of the biological parents, substance abuse by biological parents, and the criminality of the biological parents. Other instruments measured emotional and behavioral problems, psychiatric disorders, intelligence, and personality traits. 5 tables and 55 references