This paper was prepared as a script for the S.D. Punekar Memorial Lecture delivered at the Tata Institute of Social Sciences, Bombay. It contains an attempt to review the state of art in trade unionism in India in the background of the mounting concern within and outside trade unions about the relevance of trade unionism in its present form. This concern is a product of some significant changes in the approach to management of industrial relations and the growing economic complexity in business and industry. It is argued that the primary function of trade unions is to provide a countervailing power for employees in relation to management and the society at large within the framework of the basic values of social equality, justice, fairness and human dignity. The development of trade unionism among blue-collar, white-collar and other categories of workers is briefly examined in the context of this primary function. The various social and political forces within and outside trade unions affecting their performance are explained in the course of the paper. Finally, some observations are offered on the role of trade unions as a part of the changing society in the foreseeable future and the crucial issues trade unions are likely to face.