Because not everyone in the college town of Cambridge, Massachusetts, can walk into student health centers, there is the Cambridge Public Health Commission (doing business as Cambridge Health Alliance or CHA). The health care system operates the Cambridge Public Health Department and three hospitals -- Cambridge Hospital, Somerville Hospital, and Whidden Hospital -- with a combined total of more than 490 beds. It also operates 20 primary care and specialty practices specializing in such areas as pediatrics, gerontology, family medicine, psychiatry, and dentistry. CHA is a teaching affiliate of Harvard's Medical School and School of Public Health, as well as Tufts University's School of Medicine.