AbstractThe 1971 and 1981 Census of Agriculture data are used to quantify the impact of the relative size of market on the structure of the Alberta cereal agriculture. The absolute size of market and the minimum efficient size of grain farm are introduced as separate variables. Three methods are proposed to measure the optimal farm size. The results would tend to indicate that where the relative size of market has changed the concentration has usually changed in the opposite direction. The study implies that cereal agriculture is increasingly taking on the characteristics of the nonfarm sector.