In territorial birds, both parental and territory quality often covary and influence resource allocation to offspring, and the relative contribution of these components of variation in parental investment remains obscure. Thus, we disrupted the normal covariation between parental quality and territory quality to test the hypothesis that territory quality influences female prenatal and postnatal reproductive allocation. Territories were categorized into low, intermediate, and high quality based on fledging success of nests over the previous six years (nesting sites are fixed in space). To disrupt covariation between territory quality and individual quality, nestbox entrance size was increased on high-quality territories and left small on poor-quality sites because house wrens (Troglodytes aedon) prefer small over large entrances to their nest sites. Eggs from nests on high- or low-quality territories were measured and cross-fostered with eggs on intermediate-quality territories to disentangle prenatal and postnatal effects of variation in territory quality. We found a significant prenatal effect of territory quality on nestling provisioning: when reared on intermediate-quality territories, nestlings hatching from eggs produced on low-quality territories were provisioned at a higher rate than those hatching from eggs produced on high-quality territories. We propose that the increased provisioning was brought about by increased nestling begging mediated by a maternally derived compound, such as corticosterone, transferred to the eggs of stressed females in poor-quality habitat.