The authors study the association between physician leadership styles and leadership effectiveness. Executive directors of community health centers were surveyed (269 respondents; response rate = 40.9 percent) for their perceptions of the medical director's leadership behaviors and effectiveness, using an adapted Multifactor Leadership Questionnaire (43 items on a 0-4 point Likert-type scale), with additional questions on demographics and the center's clinical goals and achievements. The authors hypothesize that transformational leadership would be more positively associated with executive directors' ratings of effectiveness, satisfaction with the leader, and subordinate extra effort, as well as the center's clinical goal achievement, than transactional or laissez-faire leadership. Separate ordinary least squares regressions were used to model each of the effectiveness measures, and general linear model regression was used to model clinical goal achievement. Results support the hypothesis and suggest that physician leadership development using the transformational leadership model may result in improved health care quality and cost control.