This study examines the relationship between corporate social responsibility and financial performance by analyzing the intra-industry wealth impact of additions and deletions to the Domini Social 400 index. Results from the event study analysis indicate that additions to the index generate a positive share price response for the announcement firm and a negative response by rival firms. The opposite reaction is observed for index deletions. Additionally, the share price response is more pronounced for informationally opaque industries. Our study highlights the importance of external monitoring agencies in providing meaningful information that helps resolve investor uncertainty regarding the quality of a firm's relationships with its primary stakeholders. Copyright © 2011 John Wiley & Sons, Ltd.