Physiological, behavioral and production traits of White Leghorn cockerels from lines selected for high and low antibody response to sheep red blood cell antigen were measured to 70 days of age in several husbandry settings. Chicks were reared in pens with wood shavings, in windowless rooms, with continuous light and feed and water available <i>ad libitum</i>. Socialization, to enhance chicken-human relationships, and auditory playbacks of contentment calls were used as husbandry procedures in the context of environmental enrichment. Socialization involved gentle handling of a sample of the birds while playbacks were of 30 minute duration. Both were conducted three times per week with socialization performed from 1 to 28 days and playbacks from 1 to 70 days of age. The experiment was a 2 x 2 x 2 factorial with two stocks, socialization-nonsocialization and playback-no playback. To minimize extraneous effects, the area where the flocks were located was restricted to personnel involved specifically with this experiment. That is, the same individual (usually John Michael Metz) who obtained the data also performed the routine husbandry. None of the husbandry settings appeared to create a stress as measured by heterophil/lymphocyte ratios and production of antibody to sheep erythrocytes. Behavioral and production criteria showed that chicks responded favorably toward socialization and playbacks as measured by feed conversion and comfort scores, with the effects of the stimuli paralleling each other. The lack of additivity suggests an optimum intermediate of stimuli. Contentment to distress call ratios decreased with age. Concomitantly there were increases in social encounters among flock-mates which were probably associated with the formation of peck-rights. Genotype by husbandry setting interactions were fairly common suggesting that the degree of response to these stimuli varies among populations. This result was not surprising because of the intense selection in closed chicken populations. The data suggest that playbacks of contentment calls or enhancement of the chicken-human relationships can increase the well-being of young flocks of chickens. The degree of response, however, may vary among populations. / M.S.