For the successful realization of large engineering and construction projects (LECPs), a systemic organizational learning framework for institutional cooperation is critical. Due to the long project life-cycle of LECPs, this is particularly important for this kind of project. The objective of this paper is to analyze to what extent the conformity assessment of LECPs, carried out under Engineering, Procurement and Construction management (EPCm) services, can be used as a tool for organizational learning and cooperation between typical stakeholders (project owners, engineering contractors, EPC contractors; subcontractors and certification bodies). The research, from which this paper emanates, was based on a case study concerning LECPs in an oil and gas company in Brazil. Based on its results, we suggest that the proposed organizational learning framework, supported by the conformity assessment rationale, constitutes an important management tool that can be disseminated in other organizational contexts where conformity assessments of LECPs take place.