From 1986 to 1995 the Oklahoma five-year moving average wheat grain yield declined from 32.6 to 26.7 bu./ac. This study was conducted to determine why the state average wheat yield declined. Changes in government program provisions and changes in production practices were investigated. Changes in acreage base and changes in program diversion requirements were associated with changes in planting date and changes in the proportion harvested for grain that had been fall/winter grazed. Yield responded to these induced changes in production practices. Yield was inversely related to the proportion of the state's wheat acres planted prior to 1 October and inversely related to the proportion of acres harvested for grain that had been winter grazed.