Immediately after the election to the tenth Israeli parliament (Knesset), 21 students of political science, 24 Knesset members, and seven parliamentary correspondents were each asked (a) to assess the political power ratios of the 10 parties represented in the Knesset and (b) to judge the ideological similarity between them. As ascertained by Saaty's analytic hierarchy scaling technique, the power ratio judgments proved sufficiently consistent to justify the construction of individual ratio scales of perceived political power. The ideological proximities were adequately represented by two-dimensional ideological spaces. Analyses of the derived power measures showed that the higher the political sophistication of the subject, the higher the combined power attributed to the religious parties and the lower the combined power assigned to the two largest parties Likud and Labor. The derived power measures were then compared to the predictions of six power indices, three of which only consider the ideological space. Of the six models, the generalized Banzhaf power index best accounted for the perceived power of 62% of the subjects, whereas the classical Shapley-Shubik index provided the best fit for 31% of the subjects. The generalized power indices were found only partly satisfactory with a need for further revision.