This research was undertaken to construct a set of scales for rating the PM Functions in discussion groups on the basis of the mutual appraisal by the group members. A series of factor analyses were made with respect to the rating items devised for Studies 1 to 4. The results of the analyses show that the rating scales used were effective in measuring the Performance (P) and the Group Maintainance (M) Dimensions in group discussion. Summarizing the results of our tests on the PM Rating Scales devised for the measurement of the discussion group and those of Burk's study (1967), seventeen items for the rating of the P Dimension and fourteen items for the rating of the M Dimension have been sorted out.