Abstract
Citizen science, defined as participation of the general public in scientific research, could significantly help scientists to address biodiversity issues, through (i) monitoring the state of biodiversity, (ii) framing indicators which synthesise and communicate information on the state of biodiversity, (iii) building scenarios to evaluate the plausible consequences of different policies. A key asset of citizen science is that participating citizens disseminate the information they gain, thereby increasing the profile of issues being researched. We review further benefits associated with biodiversity monitoring, indicators and policy scenarios, envisioned as collaborative tools between scientists and citizens. Such collaboration promotes both the scientific adequacy and social legitimacy of these tools, so that they can meaningfully inform debates and decisions on public policy.