This article explores the adoption of geographic information system (GIS) knowledge and skills through in-service training for high school geography teachers in Taiwan. Through statistical analysis of primary data collected from a census of Taiwan's high school geography teachers, it explores what motivates these teachers to undertake GIS training. The design of the questionnaire was largely inspired by the technology acceptance model (TAM) and the social influence model (SIM). The former model postulates the influence of perceived usefulness (PU) and perceived ease of use (PEOU) of GIS on teachers' actual adoption of the technology. The latter, in contrast, postulates that teachers' usage of GIS is affected by their peers and their schools. Statistical findings indicate that PU and school support are important factors influencing teachers' adoption of GIS in Taiwan. (Contains 8 tables and 4 figures.)