Background: Children from low-income families participate less often in physical activity than children from high-income families. In the Netherlands, cross-sectoral interventions were implemented to stimulate physical activity among children from poor families. Purpose: To get insight into the implementation and successfulness of these interventions with regard to increasing physical activity among the target group. Methods: Four interventions were studied during the two-year funded period. Group interviews were conducted one and two years after the start of the intervention with: 1) project coordinators and collaborating partners; 2) participating children; and 3) parents. The group interviews focused on implementation and reach of the intervention, involvement of parents, and factors influencing physical activity participation among the target group. Results: Interventions were often adapted to the local context. Furthermore, there was little collaboration with key figures in the neighborhood that were ... : The Health & Fitness Journal of Canada, Vol. 14 No. 3 (2021): Proceedings from the 8th International Society for Physical Activity and Health Congress ...