This article draws upon recent work in the cognitive neurosciences to suggest that the facilitation effect follows naturally within current psychological theory. A view of the mind as consisting of discrete mental modules, called psychological modularity, is defended with case study evidence of double dissociation. It is argued that transfer of academic subject knowledge occurs in bilingual settings as an epiphenomenon of mental architecture: Because content knowledge is independent of linguistic knowledge, it is accessible to any language or languages a person happens to know. As such, transfer should be seen as a metaphor for a process; it is simply a natural consequence of our mental architecture. Cummins's developmental interdependence hypothesis, threshold hypothesis, and common underlying proficiency model are discussed. It is concluded that the facilitation effect is derived by the modularity thesis within a framework in which language is viewed as a cognitive domain separate from literacy and school subject matter knowledge.