e importance of social responsibility strategy for the sustainable development of megaprojects has been widely concerned, while types and motivations of social responsibility behavior have also been analyzed and examined in the corporate management literature. However, the typical social responsibility behaviors in megaprojects and the various motivations and factors that influence stakeholders' selection of social responsibility behavior have not been fully considered and confirmed. In this study, camouflage behavior and collaborative behavior are taken as representative social responsibility behaviors. Based on the social action theory, the impact of relevant influencing factors is empirically examined and stakeholder's selection of these two behaviors toward megaproject social responsibility (MSR) is explored. Results from the sample data of 127 management staff with megaproject experience from the participating parties revealed that synergistic behavior is driven mainly by relationship quality (RQ), whereas hypocritical behavior is affected by RQ, institutional pressure, and external appeals. In addition, the mutual feedback mechanism significantly improves the RQ of participating parties, which indirectly affects both behaviors. ese findings bear implications in realizing the management of social responsibility behavior in megaprojects and guiding the participating parties to coordinate and implement social responsibility.