The study considers how post-socialist transition has been reflected in the newly emerging concept of sustainability of agriculture, and explains the factors that accounted for the rapid development of the Czech organic sector during the transitional period (1989–1992). The paper utilises qualitative research methods. Primary data for the study have been collected and processed with the use of document analysis. Our findings suggest that the radical shift of agriculture in early 1990s was mainly driven by negative experience of the socialist model of industrial agriculture. However, the organic sector lost momentum in the later period of economic transformation (1993–1998), due to the underdeveloped institutional framework. This historical setting resulted in a strongly competitive relationship between the conventional and organic sectors in Czech agriculture. The study undermines the general notion that organic agriculture in post-socialist countries represents an outcome of policy-based measures, rather than the activities of a social (organic) movement. The conclusions of the study confirm the thesis that the organic sector cannot achieve a breakthrough in the absence of certain elements of the institutional environment (i.e. civil society, policy, consumers).