As interest in user involvement in health and social care increased in the early and mid-2000s, this study was conducted to provide an exploration of the state of service user networking and knowledge. It was particularly prompted by increasing questioning from service providers and researchers, who began to ask ask what evidence there was that user involvement improved services. This report was built from interviews and discussions with service users and service user organisations. It focusses on service user networking and service user knowledge: how they are able to bring people together to work collectively for change, and how they are able to help service users make their voices heard and make known their experience, views and ideas. It also explores service users’ ideas for improving networking and confirms the importance that they attach to developing a national service user network and user-led database to help make this happen, and reports on their ideas, experience and perceptions of improving participation and building on service user knowledge.