This study investigates the impact of three institutional pressures, namely government, customer, and competitor pressures, on the environmental and operational performance of firms. These three institutional pressures are examined by implementing green supply chain management, considering the role of top management and studying social capital between buyers and suppliers in the supply chain. Data were collected through an electronic mail survey from buyer firms in the manufacturing industry in Korea. With 241 complete and usable responses, we used structural equation modeling to test our hypotheses. Our findings revealed that the majority of our hypotheses were supported, which is in line with the existing literature. However, the impact of coercive pressure on top management support and the impact of structural social capital on performance were found to be insignificant. The major contribution of our study is that it broadens the framework of green supply chain management (GSCM) by integrating major and recent constructs in the GSCM theory, while also providing instructive managerial implications through empirical evidence.