Despite their common goal, reformers promoting school choice and those seeking ways to improve schools through more effective principal leadership have remained for the most part disconnected. This paper presents findings of a study that examined differences in teachers' ratings of effective principal leadership in magnet and nonmagnet schools in Cincinnati's (Ohio) system of school choice. The study also examined the influence of school demographics, student achievement, teacher professionalism, and workplace conditions on teachers' ratings of effective principal leadership. The sample included 10 magnet schools and 10 nonmagnet schools. A survey of all teachers in the sample schools (n=628) elicited 417 returns, a 66 percent response rate. Nonmagnet principals were rated as more effective leaders by their teachers than were nonmagnet principals. There was a lack of correlation between teachers' ratings of effective principal leadership and student outcomes. Indicators of teacher professionalism appeared to be the strongest predictors of effective principal leadership as rated by teachers, particularly teachers' perceptions of their opportunity to learn. Goal congruence and resources were significant predictors in both school types, and may be even more critical factors in nonmagnet schools. In magnet schools, greater school size was correlated with lower ratings of principal effectiveness. The discussion offers possible reasons for the findings. Four tables are included. (Contains 29 references.) (LMI)