This article reports on professional development in which twenty-four middle- or high-school teachers learned about integration of the Geographic Information System (GIS) in science or social science classes. We analyzed qualitative data obtained from the participants to examine two research questions. 1) What were the most relevant and useful skills and knowledge the teachers acquired from this professional development? And, 2) what were the approaches they intended to use in integrating GIS with instruction. We sought to understand the properties and impacts of our professional development designed through Technological Pedagogical Content Knowledge (TPACK). The article concludes with implications for further research on geospatial training in the TPACK theoretical framework.