The efficacy of bromocriptine in the treatment of stereotypy and self-injury is determined in a randomized, double blind, placebo controlled, crossover study extending over 20 weeks. Cohorts of 6 to 8 patients first enter into a single blind placebo phase, followed by double blind treatment with placebo or bromocriptine. The crossover manipulation entails a titration phase, a maintenance phase, then a final single blind placebo condition.