A wheat supply model based on regional planted and harvested acreage equations represents Part I of a two part wheat econometric framework being developed to measure the factors affecting wheat production and price (demand) levels. The major characteristics of several types of wheat acreage adjustment programs in recent years have been quantified into two broad acreage policy measures - an “effective support rate", and an "effective voluntary diversion rate”. These variables along with several other economic and weather condition variables have been used to develop planted and harvested acreage equations based on the 1950 to 1970 period. The policy variables differ somewhat with respect to their impact on wheat acres planted among the major wheat growing areas, but are generally important factors affecting planted and harvested acres. Wheat market price expectations represented by the U.S. prices received by farmers the previous year also are important factors affecting wheat acres.