We studied the management of internal R&D stakeholders and their involvement dynamics in breakthrough R&D projects. Building on a longitudinal research partnership with a global car manufacturer since 2005, this research highlights the important dynamics of involvement among internal R&D stakeholders in the engineering development organization. Some stakeholders — who served as experts, innovation design strategists or internal collaboration strategists — succeeded in involving the individuals needed for the project’s progress, sometimes generating an over-commitment. The success of the rationale of these stakeholders on engineering resource involvement depended on the perceived legitimacy of their owners.