Collaboration in primary health care is recommended to achieve global health goals. Public-private partnerships (PPP) are one means of collaboration. Our study examined collaboration in a case study PPP for primary health care in Western Province, Papua New Guinea (PNG). Interviews with key informants involved in the PPP were conducted and key programme documents were reviewed. Data were coded and deductively analysed using the collaborative governance model developed by Emerson, Nabatchi and Balogh. The key features of the case study PPP that were highlighted by the collaborative governance model were: identification of partners, trust, procedural arrangements, and leadership. We identified four lessons of significance in the practical establishment and implementation of a partnership in a complex and challenging setting such as PNG: the need to (i) prioritise in-person collaboration and communication, (ii) engage dynamic individuals to lead the partnership, (iii) encourage relationships across all sectors and actors, and (iv) remain flexible and adapt to local cultural and context. Collaborative governance offers a practical framework to understand, assess and strengthen collaboration in multi-stakeholder partnerships in the health sector.