The study describes an evaluation of a 48-week physical activity and nutritional education programme for overweight/obese school-age children using quantitative and qualitative methods. The majority of participants were obese or severely obese when enrolled, and while some improvements in body mass index, self-esteem and engagement in a range of physical activities were noted, difficulties in evaluating a complex community-based intervention were highlighted. Children, parents and health professionals described a range of benefits from attending the programme but more intensive services are likely to be needed for the most seriously obese children and for those families resisting intervention.