This paper inquires whether psychology should be internalist or externalist, that is, whether it should consider mind as an entity in itself, or rather as a relation with the environment. Some influential theoretical arguments for internalist psychology are critically reviewed and it is concluded that there is no compelling reason for internalist psychological taxonomies. Next, some proposals for a functional or relational type of explanation in psychology are explored, and it is argued that they provide a workable alternative for internalist explanations. Finally, Gibson's ecological psychology is adduced to show the empirical feasibility of a psychology that explicitly includes environmental considerations in psychological taxonomies. © 1997, Sage Publications. All rights reserved.