In this paper, we provide an ex-ante explanation for why some technologies such as James Watt's steam engine move successfully across broad technological fields, while other technologies do not. Using a sample of VC-backed biotechnology firms, we examine firm knowledge exploration choices along three dimensions the decision to build from technologies across broad fields, the decision to explore application domains that are new to the firm, and the decision to mix these two options at the same time. We argue that firm-level invention decisions find differing responses when received by the selection environment. We find evidence of a "breadth-of-impact frontier" for technologies, wherein the choice of whether a firm should enter into a new application domain than those of the past should be informed by the degree to which the technology is citing poor work narrowly or broadly. The findings suggest that the belief that broad sourcing diversity will always result in greater citation diversity requires some caveats. The results contribute to the understanding of not only how entrepreneurial firms evolve but also how individual firms contribute to collective progress. (C) 2010 Elsevier Ltd. All rights reserved.