Gave 162 male Long-Evans rats different types of experiences to alter their mouse- and rat-pup-killing behavior. First, hungry Ss given considerable experience in mouse killing did kill rat pups, whereas inexperienced Ss were unlikely to kill pups. Second, nonkilling experiences subsequently inhibited hunger-induced mouse killing. Nonkilling experience was given by presenting rat pups and mice to food-satiated Ss and by presenting rat pups to hungry Ss. Inhibition was greater when pups were presented to satiated Ss rather than to hungry, and when pups, rather than mice, were used as inhibitory stimuli. (20 ref.) (PsycINFO Database Record (c) 2006 APA, all rights reserved)