Most studies into the performance of socially responsible investment vehicles have focused on the performance of sustainable or socially responsible mutual funds. This research has been complemented recently by a number of studies that have examined the performance of sustainable investment indices. In both cases, the majority of studies have concluded that the returns of socially responsible investment vehicles have either underperformed, or failed to outperform, comparable market indices. Although the impact of sustainable indices to date has been limited, the (...) recent launch of sustainable indices by Dow Jones and FTSE suggests that more attention is being paid to the subject by financial markets, investors, and companies. This development raises a number of important issues which are reviewed in this article: (a) the performance of indices compared with their benchmark indices; (b) the methodologies employed in compiling the indices; and (c) the impact of the indices on companies and the investment community. The article concludes with a number of suggestions for areas that merit future research. (shrink)