This article challenges the growing consensus in the literature that medieval manorial managers were price responsive in their production decisions. Using prices of and acreages planted with wheat, barley, and oats on manors held by the bishop of Winchester from 1325 to 1370, price elasticities of supply are estimated for each grain in aggregate and on each particular manor. Aggregate price elasticities of supply for wheat, barley, and oats were rarely statistically significant and when significant were very low compared with elasticities estimated for developing and developed countries in the nineteenth and twentieth centuries. The low levels of agricultural supply response in fourteenth-century England suggest that commercialization was not as dominant in the medieval economy as has been argued. Thus, structural changes in the economy, such as the leasing of demesnes, the growth of wage labour, and the end of villeinage, may have been more important than price fluctuations in driving long-run economic change after the Black Death. Likewise, a shift from low price responsiveness to higher price responsiveness could have been an important part of the capitalist transformation of agriculture in the early modern period.