The purpose of this study was to determine if there was a relationship between four selected personality categories as measured by Myers-Briggs Type Indicator® (MBTI) and gender to leader effectiveness and flexibility as measured by Leader Behavior Analysis II Self-A® (LBAII Self-A) and years of experience in school administration. A review of literature traced leadership to the Situational Leadership II model utilized in this study. The model was based on selecting the appropriate leadership style for the individual situation and development level of followers. MBTI® measured sixteen combinations of four personality types which included Extravert® or Introvert, Sensing or iNtuitive®, Thinking or Feeling, and Judging or Perceiving. Four types were selected for this study (ISTJ, ESTJ, INTP, and ESFJ). The LBAII Self-A® instrument measured leader effectiveness and flexibility. The sample was 80 Texas school administrators in eleven school districts. Statistics utilized to test the hypotheses included Hotelling's T2, Multiple Analysis of Variance, Analysis of Variance, and Multiple Regression. Independent variables were gender and personality type. Dependent variables were leader effectiveness, flexibility, and years of experience in school administration. Findings reported a significant difference in leader effectiveness scores of the ESTJ personality type. Additionally, Judging/Perceiving was a significant predictor of years …