Drawing on the open innovation literature, we examine the relationship between alliances with science-based and market-based partners on the one hand, and impactful and lower-impact innovations, on the other hand. Specifically, we predict that alliances with science-based partners will boost impactful innovations while alliances with market-based partners will boost low-impact innovations. We also examine how the social capital of the Board of Directors moderates these relationships. We base our analyses on a large dataset of Chinese firms constructed from diverse sources and find strong support for our hypothesized relationships. We identify the theoretical and managerial implications of our study.