Past research on idea implementation has focused on employees trying to win social support for their own ideas, yet employees are often handed ideas to implement that were developed by others. We propose and test hypotheses on such handoffs, focusing on how handing employees relatively mature ideas to implement may lead them to build less creative final products. We tested our hypotheses using two studies: an archival study of 5,676 movies in the U.S. film industry and a complementary experiment. Results suggest that late handoffs yielded less creative final products than no or early handoffs, meaning it was costly to creativity when employees implemented relatively mature ideas without driving at least some of their prior development. However, “serialized late handoffs”—wherein implementers were handed relatively mature ideas after an earlier handoff between two other individuals—were less costly to creativity than late handoffs from one other individual. Mediation results suggest that late handoffs reduced implementers’ creativity by restricting their sense of psychological ownership and the coherence of their final products. This research advances theory on idea implementation, handoffs, and psychological ownership in creative work.