Both price incentives and increases in efficiency have been responsible for increased livestock production and feed use in the European Community. Econometric estimates from 1964 to 1979 suggest that increased efficiency was a more important factor for poultry meat, eggs, and pork, while price incentives were more important for beef and dairy. Feed demand for grains and oilseed meal responded mainly to the growth in livestock products, but was limited by increases in the use of nongrain feeds. Simulation results suggest that lower price supports would have significantly reduced milk production and feed use, while an increase in the price of oilseed meals would have had little effect on the demand for total oilseed meal.