Societal ecosystems are struggling to solve complex problems that could benefit from research by information systems (IS) scholars. However, existing IS research methodologies seek to reduce complexity and so are unsuited to the holistic investigation of complex phenomena. This paper presents a research methodology based on principles of complexity theory consisting of three non-linear phases, namely sensemaking, action and reflection. This complexity-aware methodology requires innovative methods of data collection, analysis and presentation. In order to demonstrate the application of the methodology, an action research project, which investigates the complex challenge of enabling elderly citizens to use IS for social wellbeing, is described. Thus, in addition to the methodological contribution, the results of this IS research provide an instance where IS can contribute to enhanced societal value.