In "The Relation of Theory to Practice in Education," John Dewey compares professional education for teachers to the education of other professionals, especially physicians. He distinguishes between 2 general approaches, the apprenticeship and the laboratory, generally favoring the latter. This article proposes 6 commonplaces characteristic of all forms of professional education and critically examines Dewey's views of teacher education through those commonplaces. Proposals are offered for conceptualizing the education of teachers in general and the connections between theory and practice in particular.