Research and extension are two componentes of a matrix which includes marketing, supply, production, credit and other elements necessary for the development of agriculture. These elements constitute an interrelated system constituted by elements and their connecting relationships or processes and can only be fully understood and analysed in this context. The purpose of the system is the attainment of specific goals which can and do vary from one country to another, dependent on the interests and aims of the policy makers, and the constraints imposed on them by their reality. The functioning of the technological transfers system is looked at and analyzed and an attempt is made to indicate the principle forces which influence its functioning. The attempt is not to describe the operation of any one system in particular but delineate elements and processes common to all, and which in each case conduct themselves in accordance with the specific existing conditions. In the system there are three subsystems which awe emphasized and which constitute the principal elements of our model: the research subsystem, the extension subsystem and the client or farmer subsystem. Apart from these there are other important conditioning factors, such as the policies and priorities established by policy decision-makers; the availability and quality of the resources, and the character of the support services all of which serve as limitations or constraints on the functioning of the process. (MIBA)