The academic discussion on relational forms of project governance in general and project alliancing in particular has centred on megaprojects. The applicability of project alliancing to other types of interorganizational projects requires more attention. The aim of project alliancing is to promote goal alignment and innovativeness across project actors by sharing risks and rewards through an alliance contract. As interorganizational projects are prone to inter-actor conflicts, it is necessary to understand the utilization of project alliancing in various kinds of interorganizational projects. The aim of this conceptual study is to scrutinize the applicability of project alliancing to varying interorganizational projects. Building primarily on the project governance, relational contracting, project network, and project alliancing literatures, we analyze the common alliance applicability criteria and relational governance mechanisms, and introduce an alliance governance design matrix. The matrix combines the criteria for alliancing applicability with governance mechanisms and reveals ways of matching them in various interorganizational projects. Evaluating governance mechanisms in project alliancing and their connections with the applicability criteria helps extend the applicability of alliancing to versatile contexts and resolve potential inter-actor conflicts. For practitioners, we offer a framework for assessing the applicability of project alliancing in delivering the expected solutions, choosing appropriate governance mechanisms, and assessing organizations’ readiness to participate in alliances.