The paper outlines several studies over a two-year period to develop a self-report and observer-rating measure of sensitivity/encounter group outcome. The initial form of the scale was taken from McMillan (1971) who developed a measure of 16 categories of group outcome; McMillan's work indicated the scale had high reliability. Subsequent study supported somewhat the validity of the scale, but also indicated several areas where the scale could be improved. The scale was shortened and given a checklist format; validity was again supported in further studies. Finally, the scale was converted to behavioral items, submitted to a large sample for item and factor analysis calculations. This form yielded high reliability, and 11 factors from an image analysis solution. Extensive forthcoming research to further investigate the reliability and validity of the scale was outlined. It was concluded that the scale assessed a number of small factors relating to effective functioning in interpersonal relationships which facilitate intimacy. (Author)