40 Projects are most likely to influence policy if they receive government support, not only in the form of funding but also through active participation in the project’s design and implementation. To do so, projects must have a straightforward engagement process for participants, requiring limited effort and a priori scientific skills. Data quality is a critical issue in the policy context. Citizen science projects that aim for policy uptake need to ensure alignment with monitoring requirements and regulatory standards. In other words, they need to follow a fit-for-purpose (or fit-for-use) approach where key aspects like data quality, scale, cost, interoperability, and data format are considered. B P 53 54 Behaviour Policy C Cities Citizen Science CS CS P CS P