This article examines the relationships among adolescent environmental behaviors and self-efficacy, knowledge, and attitudes. It was hypothesized that adolescents who demonstrate more proenvironmental attitudes are more likely to demonstrate proenvironmental behaviors. It was further hypothesized that perceived self-efficacy would have a moderating effect on the environmental attitude-behavior relationship in that the relationship between proenvironmental attitudes and behaviors would be stronger among adolescents with high levels of self-efficacy. Participants were 848 students from three academically achieving high schools on the West coast. Hierarchical regression analyses were used for all subsequent analyses. Results indicated that proenvironmental attitudes significantly predicted proenvironmental behaviors and that environmental knowledge was a significant moderator for the relationship between environmental attitudes and environmental behaviors. This was especially true for males.