This paper addresses self-regulation as a complementary means to harmonize and regulate European Contract Law. In the context of the paper SR is conceived as a complementary device to legislation and as a monitoring device to verify ECL implementation. Within self-regulation different players and forms of rule-making are examined. In relation to players different private organizations are considered: independent organizations and self-interested organizations, which will be further differentiated according to the nature of the represented interests. In relation to the institutional environment a distinction is assumed between market and private non market rule-making. In the market environment private organizations provide rules, including standard contract forms for a price or more generally for remuneration, in the non market environment private organizations provide contract rules for free. The main aims of the paper are (1) to demonstrate the necessity to consider self-regulation (hereinafter SR) as a significant component of the debate concerning the definition of Common Frame of References (hereinafter CFR), (2) to identify the role and the limits of self-regulation in the formation of European Contract Law particularly associated with competition law and fairness, and (3) to show the strong correlation between the governance of self-regulatory bodies and the substance of European Contract Law (hereinafter ECL).