The purpose was to determine the effectiveness of three feedback conditions (aversive tone, preferred music, and no feedback) on time-on-task of correct upper body postural alignment in adults with profound mental retardation (PMR). Participants were seven adults (3 males and 4 females), ages 25 to 34. A randomized multiple-treatment design with generalization and follow-up phases was used. Participants received three randomly assigned conditions each day for a total of 45 sessions over 15 days. Five of the participants increased time-on-task in response to preferred music, whereas two participants increased time-on-task in response to both aversive tone and preferred music. Friedman two-way analysis of variance indicated that music was significantly more effective than other conditions. It was concluded that preferred music feedback is, at least minimally, effective in improving time-on-task of upper body postural alignment of adults with PMR.