This study hypothesized that students in a course on mental retardation (MR) who had had extended contact with retarded people would achieve more favorable attitudes toward mental retardation than students without similar contact. Students enrolled in a Psychology of Mental Retardation class were randomly assigned to a control group (n=29) or an experimental group (n=59); a group of business students (n=64) served as a second control group. All students provided demographic information and completed a community living attitude scale, that measures four attitudes (empowerment, exclusion, sheltering, similarity) toward people with MR, at the beginning and end of the semester. Experimental students completed 20 hours of community service with people with MR and kept reflective journals. The study found no between-group pretest differences between experimental and control groups; however, differences were noted between those selecting the MR course and those in the business course (those selecting the MR course had had more interaction, scored higher on the empowerment and similarities scales, and lower on the exclusion scale). Students' previous school experiences with people with MR did not predict attitudes or attitude change. However, previous experience with mentally retarded people did predict posttest results for control group students, with those having the least experience reporting higher exclusion scores. (Contains 29 references.) (SM)