Approximately 140 gynes of the paper wasp, Polistes fuscatus, were overwintered in the laboratory with their natal nest and nestmates. After a 14 day isolation period, three marked female nestmates were placed into a nesting box with three marked female nestmates from a presumably unrelated colony. Fifteen nesting boxes were constructed, each with six gynes from two different sister groups. The identities of paired gynes (spaced ≤5 cm apart) and foundresses on nests were recorded in blind observations. Sisters preferentially paired (P <.0001) prior to nesting. Of 18 foundress associations formed at newly constructed nests, 16 consisted of sister groups.