With major medical organizations predicting a national shortage of physicians in coming years, a number of institutional models are being considered to increase the numbers of medical students. At a time when the cost of building new medical schools is extremely expensive, many medical schools are considering alternative methods for expansion. One method is regional expansion. The University of Washington School of Medicine (UWSOM) has used regional expansion to extend medical education across five states without the need to build new medical schools or campuses. The WWAMI program (the acronym for Washington, Wyoming, Alaska, Montana, Idaho), which was developed in the early 1970s, uses existing state universities in five states for first-year education, the Seattle campus for second-year education, and clinical sites across all five states for clinical education. Advantages of regional expansion include increasing enrollment in a cost-effective fashion, increasing clinical training opportunities, responding to health care needs of surrounding regions and underserved populations, and providing new opportunities for community-based physicians to enhance their practice satisfaction. Challenges include finding basic-science faculty at regional sites with backgrounds appropriate to medical students, achieving educational equivalence across sites, and initiating new research programs. UWSOM's successful long-term regional development, recent expansion to Wyoming in 1997, and current consideration of adding a first-year site in Spokane, Washington, indicate that regional expansion is a viable option for expanding medical education.