Two experiments were conducted in November 1980 and March 1981 to study media effects on the perceived legitimacy of political groups. The first experiment was a pilot study designed specifically to explicate legitimacy by factor analysis. The second experiment was designed to validate the factor analysis performed in the pilot study, to expand the number of independent variables manipulated, and to test specific hypotheses for the factors. The factor analysis of 20 measures in the first experiment yielded four factors: evaluation, legality, viability, and stability. The results of this pilot study partially supported the hypothesis that negative, ridiculing media coverage of a deviant political group could decrease its perceived legitimacy. In the second experiment, 178 business and journalism students responded to measures delineating the four factors that resulted from the first experiment. The results of this second experiment found support among all four factors for the hypothesis that negative, ridiculing media treatments could cause a deviant political party to be perceived as less legitimate. But interactions between media treatment and political party on three of the four factors emphasized the need for studying legitimacy as four separate dimensions--evaluation, legality, viability, and stability. (RL)