This article describes how applied behaviour analysis can be implemented effectively and affordably in a maintained special needs school in the UK. Behaviour analysts collaborate with classroom teachers to provide early intensive behaviour education for young children with autism spectrum disorders (ASD), and function based behavioural interventions for children between the ages of three and 18 years. Data are presented that show how the model is effective. Children with ASD under the age of seven made significant gains on intelligence quotient and on a range of skills including language, social and play, and academic skills following three academic terms of intervention. Case study data for two children reveal a marked decrease in challenging behaviour following a function based behavioural intervention. These interventions have led to greater independence, integration and access to curricular activities. These data show that children are making significant gains within this cost-effective model.