There are two different, and somewhat competing, strategic explanations for why firms certify for ISO 14001. On the one hand, firms may seek to reinforce their present strategies thereby further enhancing their competitive advantage. On the other hand, firms may use ISO 14001 as a mechanism to reorient their strategies, so that a clear signal is sent about the firm's change in strategic positioning. This paper aims to identify the most likely explanation for early adopters of ISO 14001. Using a (...) matched pair design, we test these alternative explanations on a sample of US firms that certified for ISO 14001 in the first two years after its introduction. In particular, we tested whether ISO 14001 was used to reinforce or reorient firm strategies in respect to the natural environment, corporate social responsibility, quality, and internationalization. We found that firms that certified early for ISO 14001 had considerable environmental legitimacy and a strong international presence. We also found that the firm's commitment to corporate social responsibility and quality were not significantly different between certified and non-certified firms. These findings suggest that early adopters of ISO 14001 leaned towards reinforcing rather than reorienting their firm strategy, which calls into question the ultimate reach of ISO 14001. (shrink)