The nature of agrarian relations and their impact on political development in the pre-1947 Bengal had a decisive influence on the complexion and articulation of institutional politics. The Hindu-Muslim differences in both socio-political and cultural terms laid the foundation of communal political groups. Capitalising on the disproportionate economic development between the two communities, the Muslim political forces strengthened their claims for a separate state. Among the Hindus, the rise of the lower castes and their challenge to the domination of the upper castes also had a noticeable impact on provincial political arithmetic. The aim of this chapter is to elucidate this socio-economic background, since this was both the source and context of political articulation in Bengal. Ecological and demographic influences brought about variations in the political economy of the province. By concentrating on these influences, an attempt will be made to show how they caused differential development in the rapidly changing economy of pre-partition Bengal.