This thesis attempts to describe the historical development and contemporary status of the rural lower class inhabiting the Cauca valley in Western Colombia, South America. Put at its briefest, this history is one that encompasses a trajectory beginning with slavery, passing through a century of social existence as free peasants, and gradually terminating in the twentieth century with the proletarianization of those peasants as they become landless manual labourers on sugar plantations and large commercial farms. The research involved in this work includes both archival investigation of historical sources, and anthropological field-work. Some fourteen months were spent living in a small area at the southernmost extremity of the valley where "participant observation" was carried out. The thesis is broadly descriptive in aim; no specific hypothesis has been advanced or refuted. While the historical section coi. siders events from a fairly wide point of view, the ethnography is far more detailed and tends to concentrate on peasant economics and social organization . The final chapter is concerned with beliefs and the changing ideology of production, and stands as a summary for most of the preceding chapters. The theme that runs throughout most of the work is the process whereby landed peasants become rural wage labourers, since this is not only the major component in the valley's history but is also the single most important factor influencing peasant life today. Consequently the ethnography focusses on some of the main effects this process has on the remaining peasantry, and their reactions and attitudes towards their being cast into a totally distinct mode of production and way of life.