In the UK, exclusions from school because of behaviour problems usually occur when other alternatives have proved unsuccessful. There is some evidence to suggest that behaviour problems and resulting school exclusions are associated with language impairment. In older children who are permanently excluded, expressive rather than receptive language impairment is more common and this is associated with increased rates of emotional problems (Ripley and Yuill, 2005). The language abilities of secondary age pupils at risk of permanent school exclusion who are still in mainstream educational provision have not yet been a focus of study. Fifteen pupils attending a mainstream secondary school located in an area of socio-economic deprivation were studied. All the pupils were at risk of permanent exclusion owing to significant behaviour problems. Measures of language and behaviour identified language difficulties in 10 of the 15 pupils, where five of these pupils had significant and severe language difficulties. In contrast, the remaining five pupils showed age-appropriate or typical language abilities. Although differences were identified in language abilities, severe behaviour problems were found in both the pupils with language difficulties and those with age-appropriate language. Mixed receptive-expressive language difficulties were more common than expressive only difficulties but these were not associated with a particular type of behaviour problem. For a high proportion of secondary age pupils at risk of permanent school exclusion, language difficulties are a factor in their behaviour problems and school exclusion. The preliminary findings are discussed with reference to the relationship between language impairment and behaviour problems, the criteria for defining language impairment in this population, the need for further research and potential implications for education and speech and language therapy.