Firms increasingly engage in business-to-business cooperation to develop relevant innovations. Scholars have shown that firms can improve service innovation either by cooperating with suppliers or by cooperating with competitors. However, there is a dearth of research examining the relative importance of cooperating with suppliers and competitors to improve service innovation, and how this relative importance depends on embracing product innovation. Based on a cross-industry sample of 16,062 Spanish firms, this article addresses these research gaps, finding that firms can benefit from cooperating with both suppliers and competitors to boost service innovation, without prioritizing either. However, this article also shows that, if firms embrace product innovation, they should prioritize cooperating with competitors to boost service innovation.