This paper examined the explanatory power of the theories on reasoned action approach: the theory of reasoned action, the theory of planned behavior, and the reasoned action model in predicting environmental behavior. Data were collected using survey method from 230 tourists visiting Annapurna Conservation Area, Nepal over one month period from mid-December, 2009 to mid-January, 2010. Results showed that the theories on reasoned action approach accounted for considerable amount of variation (39.2% to 44.2 %) in environmental behavior. Among the three models, the reasoned action model explained the highest amount of variation (44.2%) followed by the theory of planned behavior (40.7%), and the reasoned action model (39.2%).