The Utah Master Naturalist Program trains citizens who provide education, outreach, and service to promote citizen stewardship of natural resources within their communities. In 2007-2008, the Watersheds module of the program was evaluated for program success, and participant knowledge was assessed. Assessment and evaluation results indicated that amateur naturalists learned more during the course of the program and also consistently evaluated the program more positively than professional naturalists. These results were used to adjust the target audience in order to maximize learning, program success, and marketing effectiveness. (Contains 3 tables and 1 figure.)