Project WILD is an interdisciplinary conservation and environmental education program focusing on wildlife. The program was created for use in both formal and nonformal settings and materials are intended to support state and national academic standards appropriate for grades K-12. The Project WILD program evaluation was designed to assess (1) teachers’ reactions to Project WILD implementation and materials and (2) the effect of Project WILD on student knowledge and attitudes about wildlife. Evaluation participants were students and teachers at primary and secondary schools in Colorado, Virginia, and Washington. Data collection included student pretests and posttests, teacher logs, classroom observations, and interviews with some teachers, students and administrators. Results guided the development of separate elementary and secondary curriculum guides, a topic index that includes interdisciplinary concepts, and secondary teacher workshops that included time to integrate Project WILD with required curricula and examples of local environmental science. The secondary activity format was revised before the first printing of the Project WILD materials.