Keywords:Theory of planned behavior Environmental behavior Sustainability Empathic concern High school students Beliefs a b s t r a c t This study relied on the theory of planned behavior (TPB) to identify the beliefs that influence young people's pro-environmental behavior. High-school students completed a questionnaire regarding the performance of pro-environmental behaviors early in the school year and reported on their behavior toward the end of the year. In addition to the standard TPB constructs, the initial questionnaire assessed descriptive norms, moral norms, sex, and empathic concern. Results revealed an excellent fit for the standard TPB model; attitudes, descriptive subjective norms, and perceptions of control made independent contributions to the prediction of intentions, and intentions together with perceived control predicted behavior. Behavioral, normative, and control beliefs predicted, respectively, attitudes, subjective norms, and perceived behavioral control. Empathic concern influenced intentions and behavior indirectly by its effects on behavioral, normative, and control beliefs. Examination of the effects of specific beliefs revealed important implications for designing effective behavior-change interventions.