To carry out a three year randomised controlled trial of a specialist behaviour therapy service for adults with learning disabilities compared with treatment as usual, within South Essex Partnership NHS Trust. The study is funded by the South Essex Partnership NHS Trust (ISRCTN62134865).

Challenging behaviour is common in people with intellectual disabilities, but there is a paucity of specialist services in most areas. Currently, most of the care is provided by local community based intellectual disabilities teams whilst specialist care is usually hospital based and situated away from the clients' residence. South Essex Partnership NHS Trust provides such a specialist service to people with intellectual disabilities and challenging behaviour within a five sector locality.

68 participants will be randomly assigned either to specialist intervention or treatment as usual group. Structured interviews are conducted with clients and their carers at baseline and at three and six month follow-up. Main outcome is reduction in challenging behaviour. Secondary outcomes are reduction in carer burden and costs.

Will report on the first 2 years of a 3-year trial.

Intervention research is very scarce if not completely lacking in the field of intellectual disabilities mental health. We anticipate that the data from this study will provide evidence not only for further research but also for service developments and improvement in patient care.