This two-year collaborative project between the University of Nebraska-Lincoln and Northern Illinois University addresses the national need for qualified Earth science teachers and the improvement of geoscience education at all educational levels. K-12 pre- and in-service teachers participate in a three-week field-based, inquiry-focused geoscience course that integrates fieldwork in Nebraska and Wyoming with training on teaching methods and experiences designed to build geoscience content-area knowledge. A comprehensive research and evaluation plan identifies and capitalizes on effective teaching and learning practices to create a long-term strategy for the development of field- and inquiry-based geoscience pedagogy. The results of this project can serve as a guide for other higher-education institutions and public schools involved with teacher training and professional development.