The production of contextualised assessments of local climate change vulnerability serves to improve their usefulness in urban planning. For this purpose, a cross-sectoral participatory approach combining local and academic knowledge is vital. This study aims to contribute to the understanding of how such assessments can be effectively facilitated. Through the elaboration of a framework for joint knowledge production, the paper develops and applies ex-post evaluation criteria to analyse how the set-up and design of participatory assessments affected the identification of local climate vulnerability in two Swedish urban areas. These cases included a series of researcher-led stakeholder dialogues involving participants from various municipal departments, national agencies and research institutions. The results demonstrate that the project set-up affected the joint knowledge production by unifying relevant competences. However, occasionally, it also created conflict. The design of the dialogues influenced the understanding of local vulnerability by broadening the perspective on risks and opportunities and by creating common visual representations of abstract issues. The paper concludes that when facilitating participatory cross-sectoral vulnerability assessments, the consideration of two aspects is important. First, intermediaries, in the form of maps, interactive techniques and metaphors, can bridge organisational divides if designed with clear and negotiated aims. Second, the project set-up can spur motivation if the initial group composition is substantiated and the process is flexible enough to allow for relevant detours.