With respect to the ethical debate about the treatment of animals in biomedical and behavioral research, Harry F. Harlow represents a paradox. On the one hand, his work on monkey cognition and social development fostered a view of the animals as having rich subjective lives filled with intention and emotion. On the other, he has been criticized for the conduct of research that seemed to ignore the ethical implications of his own discoveries. The basis of this contradiction is discussed and propositions for current research practice are presented.