Аннотация:Based on a multiyear, qualitative study of urban elementary schools, this article examines the extent to which and the ways in which principal leadership for professional development at four schools addressed three aspects of school organizational capacity: teachers' knowledge, skills, and dispositions; professional community; and program coherence. Findings from the study indicate that effective principals can sustain high levels of capacity by establishing trust, creating structures that promote teacher learning, and either connecting their faculties to external expertise or helping teachers generate reforms internally. Study results also suggest that during transitions in school leadership, incoming principals must be cognizant of shared norms and values among their faculties before initiating new practices in curriculum, instruction, or school organization. Finally, study findings indicate that in future studies of principal effects, it may be useful for researchers to employ professional community and program coherence as mediating variables between principal leadership and student achievement.