Companies are being increasingly pressured to consider environmental concerns in their manufacturing activities and, more recently, with regard to their supply bases. Despite the broad range of literature that links performance to both green manufacturing capabilities such as pollution prevention and green supply management (GSM), managers are having difficulties developing a greener supply chain. The objective of this paper is to provide a model for development of GSM capabilities. Using the resource-based view of the firm (RBV) as the theoretical background, we postulate that plant resources are positively related to green manufacturing capabilities, which in turn are positively related to GSM capabilities. The data from a survey of a sample of manufacturing plants indicates that a managerial philosophy that includes external knowledge exchange directly supports both greener process management and environmental collaboration with suppliers. However, this managerial philosophy is only indirectly related to supplier selection and monitoring. The managerial implications of these findings are twofold: managers seeking to implement GSM need to view internal investment in green process management as a step toward environmental management of their external supply chains. They also must realize that green process management requires the support of other resources, such as environmental investments and top management commitment.