Many people with intellectual disability have challenging behaviour which often has serious consequences such as the prescription of long term medication, in-patient admissions and disruption of normal daily activities. Community intellectual disability services may have difficulties in helping people with challenging behavior. Available research suggests that Positive Behavior Support (PBS), a training system that teaches staff how to manage these situations, can benefit service users who may show improvements in challenging behavior and quality of life. The investigators do not know of any study so far that has examined the clinical and cost effectiveness of PBS that is provided by staff in routine clinical practice in community intellectual disability services. If PBS proved to be better than treatment as usual, it would have important implications for the management of a very vulnerable group of service users. In this trial, health staff will receive accredited training in PBS available in a manual written by PBS experts. It will give details of how to understand challenging behavior and develop a management plan and how to implement it and monitor whether it has achieved its goals. Twenty community intellectual disability services and 260 service users with mild to severe intellectual disability and challenging behavior will be invited to take part in the study. The sample size calculations are based on our pilot study and allow for non participation of 10% and inflation due to the number of community intellectual disability teams and staff that will take part. The teams will be randomly allocated into one of two conditions. Half will be in the PBS arm (but will also have treatment as usual) and half will be in the treatment as usual only group. The investigators will carry out assessments of challenging behavior, use of services, quality of life, mental health, aggression and family and paid carer burden at six and 12 months. The investigators will monitor treatment fidelity and the investigators will talk to a sample of paid and family carers, service users, staff and managers about what they think of the treatment and how best the investigators can deliver it in routine care. The main outcome is reduction in challenging behavior at one year after the randomization. The investigators will also carry out a health economic evaluation to examine the costs and consequences of staff training in PBS.

Please see published protocol at:

http://www.biomedcentral.com/1471-244X/14/219

Inclusion Criteria:

• Service users: Eligible to receive care from intellectual disability services; mild to severe intellectual disability; aged 18 years and over; total ABC score of at least 15 (indicates a degree of challenging behaviour occurring at least weekly including verbal or physical aggression, hyperactivity, refusal to attend activities, non responsiveness that requires professional input).
• Service: Willing to participate; availability of at least two staff members willing to train; written agreement by the service manager to participate.

Exclusion Criteria:

• Service users: primary clinical diagnosis of personality disorder or substance misuse; relapse in pre-existing mental disorder; decision by clinical team that a referral to the study would be inappropriate, e.g. there is an open complaint investigation
• Service: there are no team members willing to train; the service has already received and implements accredited PBS for their service users.