Strategy scholars have argued that capabilities can influence firm performance through a variety of means and mechanisms. However, the role of capabilities and their proposed contributions have been narrowly theorized and insufficiently tested. We contribute to resolving these issues by considering the conditions under which ordinary and dynamic capabilities contribute to higher relative firm performance. We do so by examining the positive and negative contributions of capabilities to relative firm performance as well as the effects of environmental dynamism and the degree of capability heterogeneity. We utilize measures of relative firm performance at both the process and firm level within a sample of Chilean firms, which due to a dynamic environment allows for a clearer link between the environment and the use of capabilities. We find that environmental dynamism negatively affects the contribution of ordinary capabilities and positively affects the contribution of dynamic capabilities to relative firm performance. Further, heterogeneity strengthens the contribution of dynamic capabilities to relative firm performance, but is less important for ordinary capabilities. Interestingly, we find support for the direct effects of capabilities to be stronger with a process-level performance measure, whereas the influences of environmental dynamism and heterogeneity are stronger with a firm-level measure. Copyright © 2010 John Wiley & Sons, Ltd.