BACKGROUND Overweight and obesity in youth has increased dramatically. Therefore, overweight prevention initiatives should start early in life and target modifiable energy balance-related behaviours. Parental participation is often advocated as important for school-based interventions, however, getting parents involved in school-based interventions appears to be challenging based on earlier intervention experiences. The purpose of this study was to get insight into the determinants of and perspectives on parental participation in school-interventions on energy balance-related behaviours (physical activity, healthy eating, sedentary behaviours) in parents of ten- to twelve-year olds in order to develop an effective parental module for school-based interventions concerning energy balance-related behaviours. METHODS Four countries (Belgium, Hungary, Norway and Spain) conducted the focus group research based on a standardised protocol and a semi-structured questioning route. A variation in parental socio-economic status (SES) and parental school involvement was taken into account when recruiting the parents. The audio taped interviews were transcribed, and a qualitative content analysis of the transcripts was conducted in each country. RESULTS Seventeen focus group interviews were conducted with a total of 92 parents (12 men, 80 women). Physical activity was considered to be a joint responsibility of school and parents, nutrition as parent's responsibility but supported by the school, and prevention of sedentary behaviours as parent's sole responsibility. Parents proposed interactive and practical activities together with their child as the best way to involve them such as cooking, food tasting, nutrition workshops, walking or cycling tours, sport initiations together with their child. Activities should be cheap, on a convenient moment, focused on their children and not on themselves, not tutoring, not theoretical, and school-or home-based. CONCLUSIONS Parents want to be involved in activities related to energy balance-related behaviours if this implies 'doing things together' with their child at school or at home.