Female laboratory rats (Rattus norvegicus; Wistar, Alderley Park) were housed as singletons or groups of three in units of two cages. Units were divided by different types of barrier which allowed varying degrees of social contact across the barrier. Singletons were established either with another singleton on the other side of the barrier or with a group of three as neighbours. Single-housing among females had markedly less effect on time budgeting and pathophysiological measures than among males in a similar, earlier study. In particular, singletons showed a less marked increase in self-directed behaviours, particularly tail chasing, and a smaller reduction in undirected movement around the cage. The smaller reduction in mobility may reflect a greater tendency for singly housed females to attempt escape. Females generally showed much higher levels of escape-oriented behaviours than males and up to a threefold increase in such behaviours when housed singly. Differences in time budgeting and in the apparent significance of social separation between the sexes can be interpreted in terms of differences in socio-sexual strategy and potential mating opportunity, with singleton males responding to their cage as a territory, but singleton females seeking to re-establish social contact. Such an interpretation is consistent with the effects of barrier type on behaviour in singleton females, in which time spent in escape-oriented behaviours reflected the extent to which the barrier facilitated, or frustrated, contact with neighbours.