Purpose-Inter-organisational collaboration (IOC) across healthcare settings has been put forward as a solution to mounting financial and sustainability challenges. Whilst ingredients for successful IOC have been explored, there remains limited understanding of the development of IOCs over time. Design/methodology/approach-The authors systematically reviewed the literature to identify models applied to IOCs in healthcare across databases such as Healthcare Management Information Consortium (HMIC) and MEDLINE, identifying 2,763 titles and abstracts with 26 final papers included. The authors then used a "best fit" framework synthesis methodology to synthesise fourteen models of IOC in healthcare and the wider public sector to formulate an applied composite model describing the process through which collaborations change over time. This synthesis comprised extracting stages and behaviours from included models, selecting an a priori framework upon which to code these stages and behaviours and then re-coding them to construct a new composite model. Findings-Existing models often did not consider that organisations may undergo many IOCs in the organisations' lifetime nor included "contemplation" stages or those analogous to "dissolution", which might negatively impact papers using such models. The formulated' composite model utilises a life-cycle design comprising five non-linear phases, namely Contemplating, Connecting, Planning, Implementation and Maintenance or Dissolution and incorporates dynamic elements from Complex Adaptive Systems thinking to reflect the dynamic nature of collaborations. Originality/value-This is the first purpose-built model of the lifecycles of IOCs in healthcare. The model is intended to inform implementers, evaluators and researchers of IOCs alike.