School principals can play an important role in promoting teacher leadership by delegating authority and empowering teachers in ways that allow them influence in key organizational decisions and processes. However, it is unclear whether instruction and student learning are enhanced by promoting teacher influence in all aspects of school organization or whether it is better for principals to directly work on certain processes while delegating influence on others. We compare pathways from principal leadership through school organizational processes to student outcomes that include teacher influence as a mediating factor to pathways that do not include teachers' influence. Our results suggest that effective principals use teacher leadership to improve the school learning climate while they work directly on professional development and school program coherence. [This paper was published in the "American Journal of Education" v123 n1 p69-108 Nov 2016 (ISSN 0195-6744) (EJ1119202).]