This paper examines the effects of principal leadership and peer teacher influence on teachers' instructional practice and student learning. Using teacher survey and student achievement data from a mid-sized urban southeastern school district in the United States in 2006-2007, the study employs multilevel structural equation modeling to examine the structural relationships between student learning and theorized dimensions of principal leadership, teacher peer influence, and change in teachers' instructional practice. The findings confirm previous empirical work and provide new contributions to research on the chain of hypothesized relationships between leadership practice and student learning. Both principal leadership and teacher peer influence were significantly associated with teachers' instructional practices and English language arts (ELA) student learning. A major contribution of this research is the strong and significant indirect relationships which mediate education leadership and student learning. The results indicate the importance of principals work for student learning because of their indirect influence on teachers' practices through the fostering of collaboration and communication around instruction. (Contains 3 tables, 1 figure and 1 note.)