Dr. Barrett is actively engaged in singular basic immunology research, currently focusing on intestinal T-cell biology to evaluate mechanisms of immune epithelial activation in the intestine. His work has been published in 44 major immunology and gastroenterology journals including the high impact publications of Journal of Clinical Investigation, Gastroenterology, and the Journal of Immunology. He was rewarded by research support as a principle investigator through the NIH for 2 RO1 grants. He has directly mentored and trained multiple post-doctoral fellows, residents, and medical students in his lab, fostering productive careers in academic medicine and gastroenterology. He is active on the clinical teaching service, serving frequently as an attending physician at Northwestern Memorial Hospital. His commitment to education in gastroenterology was notably demonstrated when he was Director of the Gastroenterology fellowship program at Northwestern University Feinberg School of Medicine from 1995-1999. In October of 2006 he was named Chief of Gastroenterology at the Feinberg School of Medicine. He became Professor of Medicine in December of 2007.

In addition, Dr. Barrett has assumed a leadership role in national gastroenterology affairs. He has served as a reviewer for the Crohn's and Colitis Foundation of America, NIDDK and NIAID Study Sections. He has been Chair or member of the CCFA training grant committee for 10 years. He served as Associate Editor for the American Journal of Physiology and the Inflammatory Bowel Disease Journal. He is also a reviewer for multiple prestigious journals including Gastroenterology, Nature Immunology, The Journal of Immunology, The Journal of Clinical Investigation, The American Journal of Gastroenterology and the Proceedings of the National Academy of Sciences.

Dr. Barrett has brought distinction to the Division of Gastroenterology, Northwestern Memorial Hospital and the Feinberg School of Medicine. His leadership in gastroenterology is nationally recognized.