Dr. Dahl graduated from Princeton University with honors where he majored in molecular biology. His thesis project was to study genes related to the development of cancer. He then attended medical school at Yale University, where he graduated in the top 10% of his class as recognized by the AOA honor medical society. His internship and residency training were at Harvard. He spent two years in general surgery training at the Brigham and Women's hospital, Boston Children's hospital, and West Roxbury V.A. Hospital. He then completed four years of training in Urology in the Harvard Longwood Area program in Urology. This program included training at the above-mentioned hospitals and the Beth Israel Hospital of Boston. He served as a research fellow at the Dana Farber Cancer Institute, where he studied the genetics of prostate cancer. He then moved to the University of Massachusetts Medical Center, where he was the head of urologic laparoscopic surgery. It was there that many firsts in New England took place: The first laparoscopic kidney donor surgery for transplant, and the first laparoscopic radical prostatectomy surgery.
In 2001, he was recruited to start the program in laparoscopic and minimally invasive surgery at Massachusetts General Hospital. His contributions have been recognized by the hospital, where he serves as Director of Robotic Surgery and Chief of the Division of Urologic Oncology. He has also been honored by Harvard Medical School with the title of Associate Professor of Surgery.