OBJECTIVES: To investigate the differences in participation patterns, environmental barriers and supports across specific activities typically done at school between children with attention deficit hyperactivity disorder (ADHD) and without ADHD. DESIGN: Prospective cross-sectional study. SETTING: The children and adolescents with ADHD were selected from those routinely referred to the Health Sciences University Research and Training Hospital's child and adolescent psychiatry department, which is a reference centre for the region. PARTICIPANTS: A total of 365 children (n PRIMARY OUTCOME MEASURES: Participation and Environment Measure for Children and Youth was used to evaluate children. RESULTS: The mean frequency of participation in five different school activities was significantly lower in children with ADHD than in children without ADHD, with moderate to large effect sizes. Children with ADHD were less likely to be involved in any activity type than children without ADHD, with moderate to large effect sizes. The characteristics of the school environment typically made it more challenging for children with ADHD to participate than for children without ADHD, with moderate effect sizes. CONCLUSIONS: Children with ADHD have challenges in classroom activities and with socialising with peers outside class, cognitive demands, sensorial qualities and safety. Relationships with friends, cultural acceptance and support could improve the school participation of children with ADHD.