A study was designed to measure the effects of the source's body type--endomorph (fat), mesomorph (muscular), and ectomorph (thin)--in relation to his perceived credibility by the receiver. Five hundred subjects were randomly selected from a basic communication course and, in groups of twenty in a classroom setting, were each given a noncontroversial speech in manuscript form together with a picture of an assigned source. After reading the message, the subject then filled out a semantic differential designed to measure four dimensions of source credibility. Besides the three body type conditions, there was a control condition in which the subjects evaluated the source in the absence of a picture. The basic design was replicated for male and female sources. Sex of source, sex of respondent, and the three body type conditions were the independent variables analyzed, and results showed that there were no differences between credibility according to body type, although the ectomorph female was rated highest on the sociability dimension of source credibility. (Author/SH)