The importance of pro-environmental behavior of tourists in nature-based public destinations is undeniable. This study investigates the role of perceived environment quality and environmental awareness on pro-environmental behavior through environmental engagement. The moderation role of social destination social responsibility on the association between environmental engagement and pro-environmental behavior is additionally examined. Based on survey responses (N = 394) from visitors of a nature-based public park (Melal Park of Sari, Iran) and using structural equation modeling, environmental engagement is introduced as a key antecedent of pro-environmental behavior. Results establish positive associations of perceived environment quality on pro-environmental behavior mediated through environmental engagement, although do not provide evidence for an indirect effect of environmental awareness on pro-environmental behavior. Destination social responsibility positively moderated the relationship between environmental engagement and pro-environmental behavior. Improving visitors' perception and impression of the park's environmental quality establishes a psychological and behavioral bond resulting in minimizing environmental damage. Merely increasing environmental awareness is insufficient to cause visitors to engage in pro-environmental behavior. Lastly, the article provides suggestions to park managers on ways to implement practical social responsibility solutions to strengthen visitors' pro-environmental behavior.