This study extended the theory of planned behavior (TPB) to embrace the pro-environmental construct in predicting visitor off-trail behavioral intentions at national parks. Quantitative questionnaire items were developed through an elicitation study and empirically tested among 325 respondents. Empirical results revealed overall predictive variance of 21.7 percent (R 2) in predicting visitor off-trail intentions. Behavioral beliefs predicted most of behavioral intentions followed by normative beliefs. The contribution of control beliefs and pro-environmental values had the weakest predictive power. Among the behavioral beliefs, visitors had the strongest belief that walking off the trails would lead to a shorter route. Friends as a reference group were the strongest normative belief that influenced off-trail intentions. Implications for future research and practice are discussed.