The active involvement of citizens in shaping government's response to the climate and environmental crisis is essential to ensure its effective implementation and to strengthen trust in public decision making. To achieve this, governments can rethink the governance of the green agenda by drawing on open government principles - transparency, accountability, and participation. This report compiles good practices identified across OECD Member and partner countries, illustrating how open government practices are used to (re)engage citizens in the green transition. Through initiatives to improve access to environmental information and open green data, the strategic use of public communication grounded in innovative approaches, and the deployment of participatory mechanisms and processes at various levels of government, the report highlights the opportunities and levers that can be activated throughout the policy cycle to ensure meaningful citizen participation in the green transition, foster a shared understanding and ownership of the issues and responses, and empower citizens to become key actors in this transition.