To test the relationship between school principals' level of ego development and their use of power bases, researchers surveyed principals and teachers in 70 schools in a southern urban area. Ego development levels were defined as either conformist or conscientious or a transitional conscientious-conformist level. Principals have seven power bases to rely on: rewards, coercion, legitimacy, others' feelings of "oneness" with the principal, expertise, information, and connections to powerful others. The 70 principals' ego development level was tested using the Loevinger Sentence Completion Test. A survey of 308 teachers in the 70 schools used the Richardson Power Profile, developed by the authors, to measure each principal's reliance on different power bases. Correlation of the results showed there were no statistically significant differences in the patterns of power base use by principals grouped according to levels of ego development. These findings indicate that principals are psychologically able to vary power base use depending on situational factors. (Author/RW)