This article explores a particular connection between friendship and social solidarity and seeks to contribute to understanding the societal significance of non-institutionalised relationships. Commonly the benefits of friendship are assumed to accrue to friends only. But this is only part of the story. Friendship, as instantiation of intimacy and site of moral learning, is conducive to solidarity understood as felt concern for unknown others. That potentiality rests on a specific characteristic: friendship’s loose institutional anchorage. Beginning with an explanation of friendship’s (...) institutional deficit, the article elaborates Durkheim’s ‘positive solidarity’ juxtaposed with Honneth’s recent take on solidarity. It then discusses the contribution personal relationships make to morality, before turning to the specifics of moral learning in friendship. Finally, the article argues that although undesirable as social organising principle, friendship’s institutional deficit renders it conducive to the relational acquisition of a comprehensive understanding of solidarity. (shrink)