The social organization of captive groups of adult male and female starlings caught in different localities was studied to understand the possible social basis of song sharing. In the nonbreeding season, the social organization was based on within-sex groups or pairs and a few intersexual pairs. The pattern of song sharing clearly reflected the social organization. Members of the social pairs of females shared most of their songs, whereas males shared songs with other males to an extent that depended on their degree of social association. Song sharing was mostly restricted to birds of the same sex. The ability for adult vocal plasticity in both males and females may reflect the variety of possible social situations in this species.