This paper examines the sources of stress and the effects of managing challenging behaviour on principals of special schools in Ireland, including schools for pupils with an intellectual disability, emotional disturbance, specific learning disability and physical and sensory disability, and children of traveller families. In this study principals rated the degree of stress and the potential stressors in managing incidents of challenging behaviour. Further, the degree of disruption to school management activities and the perceived likely effects of incidents of challenging behaviour on teachers and other pupils in the classroom were identified. A postal survey was conducted across all special schools in Ireland (N = 111), with 67% (n = 74) of principals responding. Further follow-up interviews were conducted with a random sample of principals. The study found that managing incidents of challenging behaviour was stressful for principals; it disrupted school management activities and significantly interfered with the education of pupils exhibiting challenging behaviour and that of "other pupils" (i.e. pupils not exhibiting challenging behaviour). Principals were clearly concerned about the welfare of their staff and the provision of an effective educational environment. Recommendations for future research and management of special schools are provided. (Contains 9 tables.)