The present study investigated schools as an appropriate context for an intervention designed to produce clinical and psychological benefits for children with asthma. A total of 193 out of 219 (88.1%) children with asthma (aged 7-9 yrs) from 23 out of 24 (95.8%) schools completed the study. Intervention schools received a staff asthma-training session, advice on asthma policy, an emergency beta2-agonist inhaler with spacer and whole-class asthma workshops. Nonintervention schools received no asthma-related input. Intervention children required less general practitioner-prescribed preventer medication despite no differences in symptom control compared with the nonintervention asthmatic group. Increased peer knowledge of asthma may have mediated improved active quality of life in the intervention group, together with increased self-esteem in young females. Those females not receiving the intervention, but identified as being asthmatic within the classroom, and thus possibly stigmatised, reported decreased self-esteem. Lower self-esteem in young males was associated with pet ownership. No change was found in staff knowledge, the establishment of asthma policies or school absences which were low even before intervention. In conclusion, a whole-school intervention can improve the health of children with asthma when followed with support for all children but effects are likely to be modified by sex and the home environment.