Involving a wide-range of stakeholders at different moments in the planning of urban adaptation to climate change can help to overcome different barriers to adaptation, such as a lack of common perception, or control over options. This Article argues for an approach that involves a wide range of actors throughout the planning process in order to confront the challenges of urban adaptation to climate change. It builds on the results of a three-year participatory action research project to identify the catalysts with which local administrations can overcome the lack of data, the low level of engagement around the climate issue, and the cause-and-effect linkages of climate change impacts on the urban environment. Significant factors include territorial rootedness, leveraging actors’ experience, interaction between actors, as well as the valuing of local actors as experts of territorial management rather than as novices with regard to climate change adaptation. In addition to contributing towards the engagement of a large number of stakeholders around adaptation issues, a planning process that involves representatives from various sectors and during several stages contributes to a greater understanding of these issues and their linkages. It follows that such a process will bring changes to urban practices by better articulating local concerns about climatic issues. Policy relevance: Although participation is commonly advocated in policy responses to climate change, only few empirical studies have investigated the ways in which local actors' knowledge can be integrated into climate change adaptation planning processes. The article builds on the results of an action research project carried out in Québec City, Canada, to address the relevance of involving a progressively broader range of actors as the adaptation process moves through its various phases. Given that a multitude of barriers to adaptation are at play at different times in a municipality, collaborations between local stakeholders emerge as a key factor. These collaborations provide greater insight into the linkages between climate change impacts and the urban environment and, in doing so, bring into question ordinary urban management and design practices.