This paper is based on a comparative research aimed at bringing forward and analyzing main changes occurred in collective bargaining in the recent years. The evolution of collective bargaining is then described with the help of comparative methods. Examples chosen from national reports and in particular italian and french labour system, prove that nation-wide collective agreements are significant sources in most legal systems, whether they precede legislation or accompany statute law in an auxiliary fashion. Decentralized agreements play instead a more controversial role, not easy to be compared. The function of collective bargaining has changed. From the initial purpose to balance the power of the employer, it is becoming a way to promote the competitiveness by the instrument of “derogations” from labour standards fixed by law or by nation- wide level agreement.