The increasing adoption of more open approaches to innovation fits uneasily with current theories of business strategy. Traditional business strategy has guided firms to develop defensible positions against the forces of competition and power in the value chain, implying the importance of constructing barriers rather than promoting value creation through openness. Recently, however, firms and even whole industries, such as the software industry, are experimenting with novel business models based on harnessing collective creativity through open innovation. The apparent success of some of these experiments challenges prevailing views of strategy. At the same time, many of these experimenters now are grappling with issues related to value capture and sustainability of their business models, as well as issues of corporate influence and the potential co-option of open initiatives. These issues bring us back to traditional business strategy, which can offer important insights. To make strategic sense of innovation communities, ecosystems, networks, and their implications for competitive advantage, a new approach to strategy—open strategy—is needed. Open strategy balances the tenets of traditional business strategy with the promise of open innovation.