We simulated beef cattle producersÕ returns to shortening a 120-day calving season to 45 and 60 days by replacing late-calving cows for two herd sizes. We developed dynamic simulation models to consider production and price risk. We explored outcomes from annually replacing 10% or 20% of the late-calving cows to reach the desired calving-season length. The optimal scenario depends on herd size and whether the producer wants to maximize profits or certainty equivalent. The smaller herd benefited more from shortening calving season relative to the large herd.