This paper gives a historical account of trade unionism. It considers political, economic and social developments which have moulded the growth pattern of trade unionism in India. The survey is divided into various phases in which trade union membership has increased, beginning with the early unionism, post-AITUC formation, World War II and its aftermath and the growth after 1947. An attempt has been made to relate the growth in union membership with economic conditions prevailing in the sub-periods. Statistical data are provided to substantiate the basic arguments. In conclusion secular trend in union membership has been subjected to statistical analysis. It has been concluded that the growth of union membership was influenced by the economic conditions and reinforced by political developments. On the contrary rapid increase in the number of unions has undoubtedly led to a decline in the average union membership. This has in fact contributed to the present loose amorphous state of union structure in the country.