The structural ambiguity of American professional schools is considered, with attention to the academic branches of business and medicine. Differences in the nature of clinical-academic tensions in business and medical schools are explored, along with the structural sources of these differences. Trends within professional schools during the early twentieth century are identified and compared to arrangements resulting from the institutionalization of professional schools in the late nineteenth century. The recent reemergence of practical professionalization in business schools is linked to changes in contingencies facing American business and to efforts of management schools to remain relevant to the interests of corporations. Changes in medical faculty work roles are also addressed. Consequences of developments within professional schools for letters and science faculty are evaluated. It is noted that changes in academic work roles within the clinical departments of medical schools have been accompanied by heightened tension between medical and letters and science faculties over appointment tracks and tenure. Finally, the the work environment at professional schools is considered, along with possible impacts of employment trends on the nature of knowledge produced by disciplinary subfields. A four-page bibliography is included.