The relationship between the European Commission and the various lobbying groups in Brussels is explored, and it is argued that there is now a ‘mature’ institutionalized policy-making style governing interactions between the Commission and interest groups. The formal and informal rules by which the Commission receives and seeks to organize lobbyist’s views, and interest groups influence the Commission’s development of legislative proposals are catalogued. It is found that there has been a steady evolution of some formal, but more often informal, rules and procedures for lobbying organizations. These include: willingness to participate in early discussions; presenting rational/technical arguments based on reliable data; viewing European policy as an opportunity, not a threat; formulating European, not national or particularistic, solutions; understanding the problems and perspectives of other stakeholders in the process; and investing in the entire policy-making process. This development of a stable system of interest group representation for the European Union (EU), sited in Brussels, impinges heavily not only on policy processes and outcomes but also on how democracy in the EU will be conceived and debated.