In developing countries, the use of cereals as livestock feed has long been outstripping their use as human food, a fact with profound implications for the food security of low-income people and for employment. Covering 104 developing countries, this study: analyzes the growth in cereal use for feed over the period 1966-80 with respect to regional, subregional, and income-related factors; forecasts feed use for the years 1990 and 2000, using alternative projections and assumptions; and discusses policy implications. The dynamic interaction between cereals as food supply and cereals as feed supply is illustrated by case studies of Taiwan and the Republic of Korea, showing that when income rises beyond a certain level, cereal consumption for food declines and consumption of livestock products increases, leading to increased demand for feedgrains. If this demand is not met, domestically or through imports, market forces can drive the prices of both meat and cereal beyond the reach of the poor. Possible strategies for preventing or mitigating this potential problem include (1) the use of labor-intensive, employment-generating livestock production methods and (2) research to increase feedgrain yields and/or substitute fodder and noncereal feeds. However, to formulate appropriate feed strategies, more reliable data on feed use by type of feed and by category of livestock output are needed. Included are 31 data tables and a 2-page bibliography (1980-86).