["R&D Management, Volume 56, Issue 2, Page 410-423, March 2026. ", "\nABSTRACT\nR&D collaborations involving multiple types of partners have the potential to generate impactful innovations but also pose significant coordination challenges. Taking a coordination perspective, this study develops and tests a theoretical framework on the optimal temporal coordination of partner relationships in such collaborations. We argue that the effective coordination of multiple types of collaboration partners in R&D projects requires a balanced approach, combining episodes of simultaneous involvement of all partners with periods of sequential engagement with individual partners. Moreover, we propose that the relative emphasis on simultaneous versus sequential involvement depends on project‐specific factors, including the complexity of technology development and the availability of managerial resources. Our analysis of 454 R&D projects undertaken by a major European electronics firm, in collaboration with diverse partner types (science‐based partners such as universities and research institutions, versus market‐based partners such as suppliers and customers), provides robust empirical support for these hypotheses.\n"]