The fundamental nature of decision-making on the African farm is analytically similar to decision-making anywhere. The decision-maker has control over a number of factors or resources which he can define quantitatively and qualitatively more or less precisely according to their nature and the relevant time horizon, and, subject to a series of constraints and influences, he has a range of choices in his use of these factors to achieve several identifiable objectives. To synthesize an African farm would be to identify and value these resources, objectives, constraints and the choice of crops and techniques, it being taken as axiomatic that smallholders make rational decisions and respond to economic incentives. However, too little is known about the competition for farm resources and the nature of farmers' aims and constraints to accurately evaluate the efficiency of their decisions,and the limited aims of this paper are: to examine the nature and interactions of the variables involved, drawing on the insights provided by observations of adjustments to economic pressures recorded in a number of investigations into African farming; and to indicate interesting areas for further research. l/ But first a note on the decision unit with which we are concerned.