Previous research has found that buyer–supplier collaboration in new product development can contribute to project success. Empirical evidence is mixed, however, and the concept of buyer–supplier collaboration is under-developed. This work develops a new construct, buyer–supplier collaboration quality, defined as the extent to which a buyer and supplier exploit shared resources while minimizing waste through interacting during project planning and execution. We use resource dependence theory to formulate interfirm and project-level antecedents of buyer–supplier collaboration quality and argue how it affects new product development project outcomes. Data from an empirical survey of 214 buying organizations validate the measurement structure of the new construct and support its positive associations with design quality and project efficiency. We also find that goal congruence, complementary capabilities and interfirm coordination efforts increase buyer–supplier collaboration quality, while interfirm relationship-specific investment reduces it.