This paper aims to understand the achievement of high agricultural growth alongside persistent poverty and a mediocre record of human development in West Bengal under the democratically elected Left Front over the last 30 years. Contrary to conventional explanations which centre on the nature of land distribution and rental arrangements, it seeks to explain the contrast between the expansion of agriculture and the deprivation of its mainly rural population through an analysis of the social relations of the post-harvest marketing system which links production with circulation and distribution. Based on field work in West Bengal's agricultural commodity markets over the quarter century 1981–2004, it shows how the seemingly contradictory outcome can be explained in some measure through the control over the marketed surplus by a handful of oligopolistic firms and their dominance over petty producers and labour in the agricultural production and marketing system. It also highlights how the Left Front governments, despite their attack on large-scale landed property, continued to enhance the privileges of the local agro-commercial elite which prevented agrarian poverty from being addressed.