The effect of corporate venture capital (CVC) investment on startup innovation performance has been examined in the extant literature. However, when this effect is enhanced is the important but relatively understudied question in strategy and entrepreneurship research. We build on the idea of regarding CVC investment relationships as learning alliances and introduce two situational factors as boundary conditions on the performance effect of CVC investment. In order to handle the endogeneity of CVC investment, we employ propensity score matching and differences-in-differences techniques. Based on the sample of startups in the human biotechnology industry in the United States, we find that CVC funding is beneficial for startup innovativeness when CVC investment is established after initial independent venture capital funding. Moreover, a startup's patent stock before CVC funding also influences on that effect.