US charter schools experience higher rates of teacher turnover than traditional public schools. The purpose of this study was to examine charter principals' professional dispositions and practices that might contribute to teacher turnover. Specifically we asked -- How do charter school principal professional dispositions and practices affect school working conditions and impact teacher commitment to remain or leave a charter schools? The study design was an embedded three-year case study of principal leadership in two charter schools. Data sources included principal and teacher interviews, school observations, and artifacts. Themes were derived from two constant comparative analyses, one of principal dispositions, a second of principal practices that might impact teacher working conditions. Analysis indicated that principals' dispositions were related to practices that affected working conditions, which in turn, impacted teacher turnover. Principals' dispositions -- autocratic 'no excuses' attitudes and valuing management leadership and accountability results -- led to practices that created limited support for teachers, both organizationally and personally.