Litters of rats were weaned at either 21 or 30 days of age. From each of the six 21-day and six 30-day litters, four males and four females were selected randomly for adult testing (approximately 110 days of age). Starting six days before the behavioral tests animals in half the litters from each weaning-age group were handled (gentled) for 5 min per day for 3 days. Half the animals in each litter were tested first in an open field, the other half were tested first on an avoidance conditioning task. About 2 wk after behavioral testing all subjects were blood sampled for assay of resting and stress levels of plasma corticosterone. In adulthood, rats weaned at 21 days were significantly heavier than rats weaned at 30 days. Open-field defecation was significantly higher in animals recieving prior avoidance conditioning. Rats receiving adult handling before testing scored significantly more avoidances than unhandled ones and were more active in the open field. Handling also affected plasma corticosterone values, but only in females; handled females had significantly higher plasma corticosterone levels than unhandled ones. None of the behavioral or adrenocortical measures was significantly affected by weaning age.