The aim of this study was to provide a description of the modus operandi of sexual offenders working or doing voluntary work with children and adolescents. Two stages of modus operandi were studied, that is, gaining the victim's trust and getting the victim to participate in sexual activity. Twenty-three offenders agreed to participate in this study. The most important source information was the Modus Operandi Questionnaire (MOQ) developed by Kaufman (1991). Data were also obtained from semi-structured interviews conducted with the offenders and from official sources, such as police reports and victim statements. Our results suggest that their position of trust in relation to their victim have an impact on the strategies adopted during the crime-commission process. Prevention strategies are discussed.