AbstractThe changing nature of organisations in the public sector means that collaboration has become an imperative for many. Notwithstanding considerable scholarly agreement about factors contributing to successful collaboration, a broadly accepted model of collaborative practice has not coalesced. In this paper, we put forward an augmented collaboration assessment tool. Building on existing research, we argue that systems thinking can help us better account for the dynamic and multidimensional nature of collaboration – a process in which partner organisations are interconnected and organised in a way that seeks to achieve a common purpose that they could not have achieved alone. We tested the validity of our tool using a three‐stage, iterative mixed‐methods approach. Our research confirms the value of a diagnostic tool to assist collaboration partners navigate an often uncertain terrain. It further establishes the value of our tool in illuminating a collaboration's dynamic interactions as a means to evaluate ‘collaboration health’.