This thesis engages with the issue of how cities are responding to climate change focusing on municipal-level energy transition planning in the city of Ottawa, Ontario Canada, using a case-study of participation in Ottawa's Energy Evolution Strategy. This thesis draws on 14 interviews with Energy Evolution participants and city staff as well as other primary sources. It examines engagement in Energy Evolution informed by two theoretical frames: constructivist STS and ecological democracy. Informed by STS theory, I show that Energy Evolution was purposefully created and only partially framed as participatory. Informed by the theory of ecological democracy, I show that Energy Evolution was only partly participatory as envisioned by ecological democracy theorists. Informed by this analysis, I argue for the increased role of non-state actors in transitions processes. For such processes to be effective, these actors require an understanding of, and influence on, participatory processes in environmentally empowered institutional spaces.