Teachers' perceptions of their school leaders influence student achievement in their schools. The extent of this influence is examined in this study. This quantitative study examined teachers' perceptions of the leadership style of their principals as transformational, transactional or passive-avoidant in improving and non-improving schools in relation to student achievement. The study population was a purposeful sample of 143 teachers in 16 schools in one school district. Leadership behaviors, as perceived by the teachers, were measured using the Multi-factor Leadership Questionnaire. Student achievement was measured with the Florida Comprehensive Assessment Test results for each school using three years of results. Independent t-test, multiple regressions, and an open-ended question were used to analyze the research questions. The study found that teachers in improving and non-improving schools had minimal differences in how they perceived their principals' leadership styles. All three leadership styles were statistically significant predictors of student achievement. School status was not significant in predicting student achievement indicating no difference in student achievement between improving and non-improving schools. Transactional leadership had a negative relationship while transformational and passive-avoidant leadership style had a positive relationship with student achievement. Regression analysis of the MLQ subscales for each leadership style as perceived by the teachers and the school status with student achievement found that transformational subscale intellectual stimulation and school status had a statistically significant positive relationship with student achievement. Likewise, the transactional subscale management by exception-active was a significant predictor with student achievement but had a negative relationship. Passive avoidant style also had a positive relationship with student achievement. Teacher demographics of gender, age, years as a teacher, years at current school, and level of school (elementary, middle, high) were examined in relation to perceived leadership style and school status. Multiple regression analysis found that only years at current school that was significant in how they perceived their principal's transformational or passive avoidant leadership style. No demographic variables were significant for transactional style or school status. Overall, teachers were satisfied with the principal's leadership style and effectiveness. Teachers most often cited school culture as having an influence on student achievement in both improving and non-improving schools. Limitations of the study included self-reported teacher perceptions of principal leadership style from 16 schools in one school district which limits generalizability; no controls for teacher classroom performance and no verification of respondents actually observing principal behaviors; time of year survey was given; and, the use of one instrument to measure leadership style may not reflect the actual leadership style of the principal. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]