This article provides evidence on the role of subcontracting in the auction‐based procurement setting with private cost variability and capacity constraints. We demonstrate that subcontracting allows bidders to modify their costs realizations in a given auction as well as to control their future costs by reducing backlog accumulation. Restricting access to subcontracting raises procurement costs for an individual project by 12% and reduces the number of projects completed in equilibrium by 20%. The article explains methodological and market design implications of subcontracting availability.