- Quondam Fellow, All Souls College (from 2009)
- Two-Year Fellow, All Souls College, Oxford (from 2007 to 2009)
- George Eastman Visiting Professor, University of Oxford (from 2005 to 2006)
- Remarque Professor Emeritus of Literature, New York University (from 2001)
- Professor of English, New York University (from 1991)
- Associate Professor of English, University of Illinois of Chicago (from 1975 to 1990)
- Assistant Professor of English, Smith College (from 1964 to 1973)
- Postgraduate, Yale University (from 1961 to 1964)
- Undergraduate, Wellesley College (from 1957 to 1961)
- Medieval literature
- History of rhetoric
- Memory and invention
- Medieval aesthetics
- Fellow (President (2005-6)) of the Medieval Academy of America
- The New Chaucer Society (President 1996-8)