The purpose of this study was to evaluate Zippy's Friends, a universal school programme that aims at strengthening children's coping skills. The sample consisted of 1483 children (aged 7-8 years) from 91 second-grade classes in 35 schools. The schools were matched and randomly assigned to intervention or control conditions. Coping was assessed by the Kidcope checklist for children and an adapted version for parents. Parents and teachers reported mental health outcomes using the Strengths and Difficulties Questionnaire. Controlling for the hierarchical structure of the data, latent variable regression analysis indicated that the programme had a significant positive effect on coping and on the impact of mental health difficulties in daily life. Subgroup analyses suggested that coping was improved in girls and children from the low socio-economic subgroup, whereas the impact of mental health difficulties was reduced in boys. (Contains 6 tables and 3 figures.)