Lever pressing was maintained by Sidman's shock‐postponement procedure and Herrnstein and Hineline's shock‐frequency‐reduction procedure with rats. Food deprivation to 80% and 70% of the animals' body weights on free feeding resulted in decreased response rates in both avoidance paradigms tested. Reinstatement of free‐feeding conditions increased body weights and response rates and decreased shock rates. The effects of food deprivation were not dependent upon any particular avoidance parameters, or types, intensities, or durations of electric shock. These results mean that weight control is essential in long‐term studies of avoidance behavior, and in studies of the effects on avoidance behavior of physiological interventions, such as hypothalamic lesions, that themselves may produce weigh