Non-urgent healthcare problems are responsible for more than 9 million visits to the emergency department (ED) in US hospitals each year, largely due to patients' lack of access to a primary care physician. To avoid costly and unnecessary ED usage for non-urgent health problems, a walk-in clinic run by nurses (CHEER Clinic) was developed as an extension of the services provided by an existing free clinic in a low-income neighborhood of Providence, RI, with the goal of providing uninsured patients with a convenient, no-cost means of accessing healthcare. An evaluation and cost-effectiveness analysis of the clinic's first 5 months of operation were performed. During this pilot period, 256 patients were seen. When incorporating the quality-adjusted-life-year value of preventive services rendered, an estimated $1.28 million in future healthcare costs was avoided. Dividing these cost-savings by the clinic's operational cost yielded a mean return on investment of $34 per $1 invested. Adding nurse-run walk-in hours at a free clinic significantly expanded access to healthcare for uninsured patients and was cost-effective for both the clinic and the patient. Ultimately, replication of this model in community clinics serving the uninsured could reduce ED burden by treating a substantial number of non-urgent medical concerns at a lower cost than would be incurred for treatment of the same problems in EDs.