Three studies tested the contribution of perceived autonomy support to the prediction of health-related intentions within the theory of planned behavior. Perceived autonomy support refers to the extent to which individuals perceive that significant others encourage choice and participation in decision-making, provide a meaningful rationale, minimize pressure, and acknowledge the individual's feelings and perspectives. Findings from Studies 1 and 2 demonstrated that perceived autonomy support predicted intentions to participate in physical activity behavior directly and indirectly via attitudes. Perceived autonomy support predicted intention even after statistically controlling for the effects from past behavior, descriptive norms, and perceived social support. Study 3 found that persuasive communications influenced perceptions of autonomy support, attitudes, and intentions. Overall, the findings support the incorporation of perceived autonomy support into the theory of planned behavior. Copyright © 2006 John Wiley & Sons, Ltd.