The article evaluates a Czech environmental education program focused on developing competence in issue investigation. In the evaluation, a simple quasi-experimental design with experimental (N = 200) and control groups was used. The results suggest that the program had a greater impact on girls than on boys, and that it increased their internal locus of control and awareness of local environmental issues. The program had no effect on students' self-efficacy in constructively dealing with conflicts or local environmental issues. The article discusses some potentially weak parts of the program theory, which include the dominating teacher-directed approach and the lack of opportunities for students to be actively involved in the solving of issues.