A Just‐Pope production function is used to estimate the effect of genetic improvement on the first two moments of wheat yield for the period 1950–86. The model characterizes the green revolution as the culmination of an era in which wheat breeders achieved rapid increases in yield potential accompanied by higher yield variances. To date, the post‐green revolution has been an era of slower mean yield growth, but of relatively rapid improvement in yield stability. Overall, the analysis indicates steady progress in producing “better” varieties; successive releases have improved either stability, mean yield, or both.