The DTE Freshwater Institute for Teachers is a year-long professional development program aimed at helping teachers design water-related, place-based environmental science projects for their students. To assess the program’s success, the Institute hired external evaluators from Western Michigan University to collect data about teachers’ relevant content knowledge and their experiences in the workshops and in their own classrooms. At the beginning of the summer institute and at the end of the last dinner dialog, teachers completed surveys that measured their knowledge of ecological science and pedagogy. Questions were wide-ranging and asked teachers to explain, among other things, how they would teach children about watersheds and how they would explain place-based education to parents. Teachers’ answers were scored with a rubric and then analyzed quantitatively in order to assess their growth during the program. Evaluation results were used to make adjustments to subsequent programs. For example, because the evaluation revealed that teachers did not fully comprehend the science content covered during the summer workshop, the subsequent program worked with teachers’ prior conceptions and focused more on pedagogy.