The use of anti-psychotic medication with an adult population of people with learning disabilities and challenging behaviours was investigated as part of an epidemiological study covering seven district health authorities and corresponding local authorities in North West England. The study found a high rate of prescription of anti-psychotic drugs (48.1%). Chlorpromazine was the most frequently prescribed drug, followed by Thioridazine and Haloperidol. Three variables, psychiatric diagnosis, where the person was resident (hospital disturbed ward, hospital non-disturbed ward, hostel or family home) and district of origin were found to be significant determinants of prescriptions when all other variables were controlled. Of the variables reflecting individual characteristics those significantly related to prescription suggested that the socially disruptive effects of challenging behaviour were determining prescription. The results are discussed in the context of differing prescription practices across residence and district in the context of the management of socially disruptive behaviour.