This paper is about collaboration in public transport governance. Drawing upon the emerging literature that views collaboration through the lens of networks, we explore why and how regional public transport authorities collaborate with both municipalities and public transport operators in the planning of public transport. We also explore the advantages and disadvantages of such collaborations. Based on interviews with civil servants (government officers) in the Swedish metropolitan regions of Stockholm, Västra Götaland and Scania, we conclude that collaboration is, firstly, a way for the regional public transport authorities (RPTA) to engage with the local municipalities and develop joint agreements on public transport priorities. It is also a way to build a common identity with the public transport operators, who operate services under tendered contracts. Secondly, we find that collaboration takes place during official meetings, as well as in informal conversations and face-to-face dialogues. Thirdly, the potential advantages and disadvantages of collaboration hinge on the ability of coordinating actors to put in place processes where the feasibility of plans can be established, and where a sense of common identity can be constructed.