Abstract. – The article is an attempt to understand the social structure of a little-known Hindu caste population of rural Bengal, traditionally dependent upon the jute-centered economy. The population is widely distributed in different districts of undivided Bengal and is known as Kapali and Vaishya Kapali, which are synonymous. The government of West Bengal declared both of them as Other Backward Classes (OBC). Serious research and documentary evidence on the caste population in general are numerous. In the case of the Kapali, the primary way of doing research is by using the oral historical approach. Special emphasis is given to the immigrant informants from Bangladesh. Findings suggest that the Kapali society vertically divides into major groups on the basis of geography and cultural practices. Each one was further vertically segmented into samaj and stratified again. Many vertical sections are reported. Each vertical section is called samaj and each one is socially isolated. Kulinism was practiced in the samaj. The contemporary society is undivided having no social hierarchy in West Bengal. These kinds of divisions, however, are present in Bangladesh even today. Through time, the rigidity of the samaj is diluted and a series of changes in social structure is observed. Findings also suggest that ecology and politics played vital roles in the change of social structure of the Kapali samaj. [India, Bengal, Kapali, kulinism, abhijata, moulik, samaj, char land]