Online child grooming is the process by which an adult manages to sexually victimize a minor using the Internet as a tool. The objectives of the current study were to determine and analyze the erroneous beliefs held by minors about online grooming and develop and evaluate the efficacy of a preventive program in mitigating these misconceptions. A sample comprising 395 adolescents aged 12-16 years (52.8% girls, M= 13.33 years, SD= 1.01) completed self-report questionnaires. A relatively high proportion of the sample had been sexually solicited by an adult (19%) or had engaged in online sexual interaction with an adult (13%). Most adolescents were unaware that online grooming is a form of sexual harassment and that male adolescents could also be victims of online sexual harassment. The intervention group showed a higher level of knowledge than the control group for eight of the 11 items. These findings suggest that greater awareness of online child grooming will contribute to its prevention.