The emphasis on accelerated agricultural development by developing countries was meant to achieve food security. However, food insecurity has remained a problem throughout much of the developing world and is the result of such factors as slow (as well as highly variable) growth in domestic food production, rapid population growth rates, limited financial capacity to import food and inadequate external assistance. Agricultural extension, on the other hand, plays an important role in development by assuring adequate and timely access by farmers to relevant advice, with appropriate incentives to adopt new technologies if it suits their socio-economic and agroecological circumstances. This paper discusses: the concepts of food security and food insecurity; the causes and consequences of food insecurity; the short-run and long-run measures for alleviating food insecurity; the strengths and weaknesses of some extension modalities; and the modifications to existing extension systems for the achievement of food security. The conclusions drawn are that: (a) improvements in nutritional standards and food security will involve not just a certain rate of agricultural growth, but reduction in population growth rates; and (b) modifications to extension services have the potential to improve agricultural productivity, increase farmers’ incomes, and improve food security.