This document summarizes the activities of ECSA (European Citizen Science Association) including their vision, mission, membership details, strategy, working groups, principles of citizen science, policy work, and partnerships. The key points are: 1. ECSA's vision is that by 2020, citizens in Europe are valued and empowered as key actors in knowledge and innovation to support sustainable development. 2. Their mission is to connect citizens and science by fostering active participation. 3. They have over 200 members from 27 countries working to promote citizen science through various initiatives and groups.