The ecosystem services (ES) concept is increasingly being integrated in to policy and decision making at all scales of environmental governance. Yet ES assessments are often characterised by high levels of uncertainty, are heavily value-laden and seek to contribute towards time-critical decision making and policy development. We assess the suitability of post-normal science as a broad scientific framework to guide research practice in such situations. Results of a literature review on the current use of post-normal science in ES literature are presented, and we discuss how the framing can contribute to three emergent threads in ES assessment: managing uncertainty, participation and knowledge validation, and dealing with value plurality. We conclude by arguing for the adoption of a post-normal science posture within ES research, due to its broad applicability, consistent philosophical underpinning and in-built reflexivity. A short list of questions is presented to help guide the application of a post-normal approach to ES research.