This paper utilizes linear demand and supply models, with additive independent shocks, to derive producer price and income variances of a typical commodity during and after a buffer stock control. It proceeds to use the models to evaluate International Cocoa Organization's (ICCO) Buffer Stock's decision to purchase excess stock from the market a floor price and re-sell it, in periods of low supply, at the ceiling price. The results show that cocoa producer prices and incomes were more stable during periods of ICCO buffer stock intervention than after the demise of the buffer stock. The results further indicate that stock-buying operations induced greater stability in producer incomes than buying stock-selling operations. © 2011 Society for Policy Modeling.