The life cycle and aspects of the social organization of Exoneura bicolor are described for the first time. The population studied was univoltine, with egg production occuring from late winter through to early summer. Throughout the year most nests are occupied by more than one female, and most new nests are initiated by groups of up to 6 cofoundresses. Reproductive differentiation between nestmates is very pronounced during winter, with only one or two egg-layers in each nest. These females appear to be largely responsible for maintaining their adult nestmates in Autumn. In spring, additional females are inseminated and begin to lay eggs, though some remain unmated and do not show ovarian enlargement. New nests are founded during late spring, and most foundresses are mated and have enlarged ovaries. Relatedness between nestmates was estimated using a polymorphic enzyme regression technique, and was found to be similar for both overwintered and co-founded nests, suggesting that co-foundresses originate from the same natal nests. The consequences of persistant multi-female nests and reproductive differentiation are discussed, and it is suggested that terms such as 'eusocial' and 'semisocial' are inappropriate to describe even ontogenetic stages in allodapine colony development.