“I think this is where they teach medical students to be late,” Ron, a grizzled convenience store clerk, cheerfully jokes to me in the waiting room. He spent months on the waiting list of another free clinic before the staffers there referred him to an alternative, student-run option. This is his second visit to the University of Michigan clinic, and so far he has no complaints about the quality of care he’s been receiving.

While interviewing for medical schools last fall, I observed a strange phenomenon: every institution I encountered would underscore its student-run free clinic as a major highlight of the medical education they could offer. First- and second-year students would speak rapturously about the experience they gained from clinic. Working there, they said, reminded them of why they wanted to become doctors in the first place.

“I feel like medical school can be really about yourself—how much I can learn, how much I can do,” says Chelsea Reighard, one of the student directors at the University of Michigan Student-Run Free Health Clinic. “I really wanted to serve people and work with them to improve their health.”

The “student-run” modifier is not overstated. With the exceptions of official diagnoses and prescription signing, medical students are responsible for everything that goes on in clinic. They schedule patient appointments, take comprehensive health histories, and conduct physical examinations. Though M.D.-bearing physicians lurk in the background overseeing clinical decisions and assuaging liability concerns, the initiative remains a primarily autonomous affair.

Free clinics are by no means a novelty on the medical landscape, tracing their roots to the Haight-Ashbury Free Clinic movement of the 1960s. But historically, many of them have depended on religious institutions for funding and support. Then, in 1989, a group of first-year medical students in the UC Berkeley-UCSF Joint Medical Program began providing free blood draws and screenings to the uninsured individuals who frequented a homeless drop-in center, and the free clinic model seriously began considering medical students as potential staffers.

Today, the majority of all U.S. medical schools have at least one student-run free clinic under their auspices. Some, such as the University of California, San Diego School of Medicine, have up to four.

The proliferation of these clinics can partially be attributed to a growing desire among the medical community to provide care to those who lack health insurance. Though the Patient Protection and Affordable Care Act is projected to extend healthcare coverage to 32 million more U.S. residents starting January 1 of next year, this still leaves about 30 million individuals uninsured and unable to pay for health services. What has increasingly begun to emerge is a healthcare “safety net,” a complex web of hospitals and community health centers that provide low-cost medical services to individuals regardless of their ability to pay.