This is a case study of peasant farming in Maridi District, Western Equatoria Province, Southern Sudan. The object is to explore the impact and inter-relationship of economic, environmental and ecological factors on the changes that have occurred in 'traditional' farming in the study area. Special attention is paid to internal as well as external forces leading to changes, and peasant farmers' own understanding of the change processes, as well as the externally-induced explanations of change. It is hypothesised that agricultural development in Third World countries cannot be fully appraised without an understanding of the farming knowledge and attitudes of farmers whom it is supposed to benefit. Some basic concepts are reviewed and the hypotheses and methods of data collection and problems encountered are presented, A background survey of the nature of the physical and human environments in which farmers base their decisions is provided. The spatial organisation and nature of 'traditional' agricultural changes and their importance to households' sustenance is noted. Farmers' environmental and agricultural knowledge, and some of the hazards and pressures of agricultural change from the farmers' viewpoint, and how they interpret and respond to these constraints are outlined. The socio-economic characteristics of farmers and the current farming activities and the nature of change taking place, including farmers' involvement in a cash economy, are examined. Emphasis is laid on the adaptive rationality/of existing modes of production and the importance of the web of social and economic networks surrounding the individual farmer and influencing his activities. Changes in the pattern of 'traditional' agriculture in an historical and regional perspective are elucidated. A discussion of the existing patterns and processes of agricultural change, and the diffusion of innovations through the formal and informal channels, and farmers' attitudes and response demonstrating their rationality is shown. In a broad analysis of farmers' world-view, the individual's attitude to farming is studied including the extent of his farming knowledge, his degree of interest in this activity, his needs and problems, land-use trends, and desired changes. A case study of coffee as a cash crop innovation and its socio-economic impact on 'traditional' land-use systems now and in the .future is considered. A brief concluding section summarises research findings and some of the practical and theoretical implications for policy consideration. This study mainly concludes that only by identifying farmers' management strategies, circumstances and their analysis of problems on their own behalf can a development programme and research be formulated which has technologies appropriate to them.