Male cowbirds, juveniles and adults, were maintained in 1 of 4 conditions: (a) visual and auditory deprivation from males, (b) visual but not auditory deprivation, (c) social isolation and (d) full contact with males. Their songs in the breeding season were tested with captive female cowbirds. The females responded with copulation postures most often to the songs of the males reared in conditions a and b. Female cowbirds showed no preferences for the songs of males they had been housed with. Comparisons of the behaviors of isolate and group-maintained birds when introduced into an established cowbird colony revealed that isolate males sang more and received more attacks. The critical importance of the male cowbird''s social environment for song potency was discussed. Comparisons of the song potency among the adults also showed the reversibility of early species-typical or species-atypical experience with regard to song performance.