Stereotypical behaviour problems describe a range of repetitive behaviours which appear to be non-functional and can arise for many reasons. However, many texts treat them as if they have a single causal mechnism, and so it is not surprisng that treatment may be unreliable, as it is often inappropriate or too generic if a proper diagnosis has not been established. In this presentation I will outline a systematic process to the assessment of stereotypical behaviour problems which links diagnosis to management, so that intervention can be more reliable.