IntroductionBuyers of medicines and vaccines are increasingly interested in pooling their procurement to improve access to affordable and quality-assured health commodities. However, the academic literature has provided no detailed description of how pooled procurement mechanisms are set up and develop over time. These insights are valuable as it increases our understanding of implementing and operating pooled procurement mechanisms successfully. Therefore, the aim of this paper is twofold. First, to explore how such mechanisms evolve over time. Second, to clarify the work that is needed to set up and sustain a pooled procurement mechanism. These findings have been translated into our Pooled Procurement Guidance document.MethodsThis qualitative study draws upon theoretical insights from organizational life cycles, collaborative and network governance, semi-structured interviews with procurement experts and academic and grey literature documents on pooled procurement of medicines and vaccines.ResultsWe identified four general developmental stages of pooled procurement mechanisms: promise, creation, early operational and mature. The promise stage is characterized by initiating engagement between participating actors, while they try to convert their perceived problem(s) or opportunities into a shared vision. The creation stage is where the participating actors formalize and design the mechanism through consensus-building, articulation of a shared plan, and mobilize resources to put the shared plan into action. The early operational stage is where the shared plan is being executed. The newly established or appointed procurement organization is required to learn fast from experience while showing flexibility to the changing needs of buyers and suppliers. Once operations are routinized, the mechanism enters the mature stage. During this stage, the pooled procurement organization develops into a trusted player that provides sufficient incentives for all actors involved. Importantly, pooled procurement mechanisms can stagnate or turn inactive at any time during the developmental process when alignment between actors is threatened.ConclusionsPooled procurement mechanisms evolve over time. Setting up such mechanisms is a collaborative process that relies on intentional efforts by key actors involved. To increase the lifespan of pooled procurement mechanisms, key actors need to sustain a relative alignment of goals, needs, motivations and purpose of the mechanism throughout its entire life cycle.Supplementary InformationThe online version contains supplementary material available at 10.1186/s40545-023-00574-9.