The aim of the present study was to develop and examine the initial psychometrics of an instrument, the Charter School Teacher Development Inventory (CSTDI), designed to measure the professional development opportunities available in U.S. charter schools. Exploratory factor analysis suggested that the CSTDI was comprised of five factors: traditional, content, coherence, duration, and collaboration. Confirmatory factor analysis also supported a five-factor structure of the CSTDI. This study provides promising support for a five-factor instrument that assesses professional development practices in charter schools and further research is warranted to determine its relevance for use in traditional public schools.