Japanese quail (Coturnix coturnix japonica) have finely-tuned kin-recognition abilities that may serve a role in mate choice. To investigate whether these abilities are expressed in other life stages, we examined patterns of association among quail chicks in the laboratory four days after hatching. Hatchlings were reared either in mixed-family groups, consisting of siblings and nonsiblings, or in pure-family groups, consisting just of siblings. Chicks were highly social in testing sessions, as reflected in their clumped spatial distributions, and interacted more with their siblings than with nonsiblings. Siblings in each of four mixed-family groups preferentially associated with one another over nonsiblings. No discrimination was evident among differently marked siblings in four purefamily groups. Thus, at an early age, quail discriminate between siblings and nonsiblings despite social experience of both. Recognition abilities that develop prior to or soon after hatching may facilitate cooperation among chicks, may enable siblings to track each others' traits as they mature, or both.