This descriptive study examined the interaction between 25 mentally retarded (MR) adult participants in a physical education setting and 51 physical education majors. The study was designed to identify and analyze the causal attributions of physical education majors concerning MR adults' motor performance, to identify and analyze the causal attributions of MR adults concerning their own motor performance, and to examine the expectancies of both physical education majors and MR adults for future success of MR adults' motor performance. Written questionnaires completed by physical education majors indicated that physical education majors' primary causal categories were unstable, internal, and controllable; and their expectancies appeared to vary according to MR adults' performance. In interviews, MR adults reported the causal categories of effort and intrinsic motive most often; their overall causal dimensions were stable, internal, and uncontrollable; and their expectations were significantly more positive than negative for future success on motor performance. (Author/JDD)