This thesis investigates the changing forms and roles of science, technology, and expert knowledge in agricultural development in Zambia from 1945 to the present day. The main focus is on the changing ideologies, polices, and technologies that different development agencies have used to transform agriculture in sub-Saharan Africa, and the persistent concerns about rural hunger and low agricultural productivity. My central argument is that contests over expert knowledge and technology have played a key role in the formulation and implementation of agricultural development policies in colonial Northern Rhodesia and then independent Zambia. Another argument is intertwined with this, namely that a historical approach is essential to understanding the origins, operation, and outcomes of development policies. The argument is developed in five chronologically sequenced case studies of particularly significant and innovative agricultural development projects, technologies, and research programmes. These studies in part stand alone, each filling a gap in the history of development in Zambia and sub-Saharan Africa more generally. By focusing upon common issues and questions through the studies, however, I explore broader themes in the history of development knowledge and practice, and the history of science and technology.I have framed my approach in two linked areas. The first concerns development experts, those who are responsible for creating new knowledge about peasant society and deploying new technologies and programmes to transform it. The thesis investigates how and why it is that certain people and institutions gain influence and acquire the status of 'development experts', and how the category of 'development expert' is subject to historical change. My main argument in this area is that development experts were more divided than is commonly acknowledged in histories of development which rely upon a more abstract and unitary notion of expertise. The second area of focus concerns how these 'divided experts' attempt to manage the peasantry's integration with capitalist social relations through the manipulation of the 'productive forces': technologies, production techniques, environmental resources, and methods of organising labour. My argument here is that technology has been used as a disruptive force; development programs have revolved around the introduction of new technologies as a means of reworking socio-ecological relations.