Online grooming is the process by which an adult uses the Internet to initiate a dynamic of sexual persuasion and victimisation through online contact to obtain an encounter or sexual content from a minor. Although there is an abundant literature of attempts to define the risk factors for grooming, fewer studies have addressed the risk factors qualitatively through direct interviews with offenders, victims and experts. Further understanding such characteristics of the grooming process allows the development and improvement of evidence-based prevention programmes, designed to target specific risk factors. To deepen our understanding of how risk factors operate and how offenders exploit minors’ vulnerabilities, the European H2020¹ project RAYUELA conducted 15 in-depth interviews with offenders, 8 with victims, and 23 with subject-matter experts from different European countries. The results, based on a categorical content analysis, are consistent with previously reported risk factors for victims. Social isolation was revealed as the most relevant factor. The age of greatest risk is in adolescence due to the characteristics of this developmental stage, among which sexual curiosity stands out. In relation to gender, although girls receive more requests from groomers, boys are more likely to accept them, showing a different perception of the risk. Other relevant factors found non-heterosexual sexual orientation, and poor family communication. In addition, a high percentage of offenders were found to be from the victims’ environment. Thus, a relevant conclusion is that risk factors cannot be separated from structural aspects of the offline reality, such as gender stereotypes and lack of sex education, so focusing on them in prevention may be more effective than addressing exclusively Internet aspects.