In a roundtable discussion, participants will present different models for national and sub regional science centre networks in Europe: Why they were formed, what they do and how they operate in relation to the European scene. We will look at mission statements, core business operations, budgets and staff, and discuss issues of sustainability and impact. We will present outcomes of working with national governments and stakeholders, and discuss what national networks can do better than the broader European organization. The session will serve as a meeting point for national science centre associations at the Ecsite Conference.