Charter school reforms are predicated on the existence of motivated groups or individuals that create these public schools of choice. Rhetoric concerning charter schools largely takes for granted the supply side and assumes that market forces will compel educational entrepreneurs to open schools. We argue that the motivations of charter school founders are variable and have important implications for the charter school landscape. Examining data on charter school sponsors in Texas, we estimate the impact of sponsor characteristics on the makeup of the student populations these schools serve. We apply a latent class analysis to measure motivation as an underlying variable whose outcomes we observe as qualitatively different sponsors. The analysis distinguishes between three groups of sponsors: those motivated in their capacity as school districts, those seeking to provide a general alternative to traditional district-run public education, and those offering a special service. The results suggest to policymakers that charter schools are diverse entities of education providers that serve different students. (Contains 6 tables, 1 figure and 44 notes.)