The authors investigate how a firm’s position in a network of marketing alliances affects performance for firms experiencing different levels of uncertainty. A more prominent position—having many, well-connected marketing alliances—is typically theorized to improve the performance of a firm. However, we find that a prominent network position can instead hurt performance when uncertainty is high. Practically, these results can help both researchers and practitioners identify when the risks of marketing alliances outweigh the rewards. Theoretically, they provide a plausible explanation for past research that failed to detect a positive relationship between marketing alliances and firm performance.