Past empirical evidence on supply response by size of farm in the U.S.A. provides no clear basis to conclude that supply elasticities vary systematically with farm size. In this paper, the central hypothesis that no systematic relationship exists between production response to price and size of farm is rejected. U.S. farms are disaggregated into nine economic size categories and own-price supply elasticities are measured for per farm and total agricultural output. Empirical results from this study suggest that supply response does vary systematically by farm size, with smaller farms exhibiting greater elasticities than midsized farms.