Five factors are found to have had a significant effect on U.S. acreage of wheat planted during 1961-74: (1) acreage allotment, (2) additional diversion for payment through 1970, (3) set-aside acres in 1971-73, (4) relaxation of allotment restrictions, and (5) the market price of wheat for the preceding season. Together, these factors explain over 98 percent of the wheat acreage variation during 1961-74. The wheat set-aside program reduced wheat planting by 0.28 acre for each acre set aside in the winter wheat regions and by 0.62 acre for each acre set aside in the spring wheat region. It reduced the U.S. acreage of wheat planted by 0.41 acre for each acre set aside nationally.