The webinar “An Open Science tool for SSH researchers and decision-makers: the Case Studies Atlas of Local Sustainability Transition” was held on 29 September 2026. The CASTAL project consolidates over 500 European SSH case studies (grey literature) on Local Sustainability Transition into a centralised digital Atlas. CASTAL contributes to Open Science and EOSC by enabling future research and the exploitation of results by researchers, local authorities, businesses, and citizens. In the webinar, organised by K&I and DASSI, we discussed issues and perspectives on Open Science and decision-making in the environmental field, drawing on the Atlas and ten secondary studies that have used and tested this tool.