The EEC created a common market that featured the elimination of most barriers to the movement of goods, services, capital, and labour, the prohibition of most public policies or private agreements that inhibit market competition, a common agricultural policy (CAP), and a common external trade policy.

The treaty establishing the EEC required members to eliminate or revise important national laws and regulations. In particular, it fundamentally reformed tariff and trade policy by abolishing all internal tariffs by July 1968. It also required that governments eliminate national regulations favouring domestic industries and cooperate in areas in which they traditionally had acted independently, such as international trade (i.e., trade with countries outside the EEC). The treaty called for common rules on anticompetitive and monopolistic behaviour and for common inland transportation and regulatory standards.