Sandra Cotterell, who has spent 29 years working for Codman Square Health Center, the last 12 as its CEO, plans to retire once a new CEO is hired, the Washington Street health center announced last Friday.

Cotterell’s first job was as a registered nurse at Massachusetts General Hospital and New England Medical Center in 1979. She later worked for Bay State Health Care, a health insurance company, in the 1980s, then started at Codman Health Center in 1994 as its chief operating officer.

The health center, which has a team of 300 professionals, including physicians, nurses, and specialists, was founded in 1979 by Bill Walczak. The health center credited Cotterell with leading the construction of an $18 million addition to the building, a health and education center named after Walczak, now a Dorchester Reporter columnist.. The center has clinical space and serves as the home of the Codman Academy Charter Public High School.

The center also hosts The Daily Table, a nonprofit grocery store, a community teaching kitchen, and an earned income tax clinic.

According to its 2021 annual report, the center treated 24,723 patients that year, with operating revenue at $47.9 million. About 75 percent of patients were Black and African American, and 41 percent were women. More than half of the patients lived in Dorchester and Mattapan, with others coming from Hyde Park, Brockton, Roxbury, and Roslindale. An expansion of services is set in Randolph, where there were 1,114 patients in 2021.

Overall, for 2021, the facility saw 77,728 clinic visits and 36,420 virtual visits. More than 12,000 coronavirus vaccines were administered, in addition to 5,364 seasonal flu vaccines, and 4,502 other immunizations. It also provided 4,566 cervical cancer screenings, 1,689 mammograms, and 2,795 colorectal cancer screenings.

“It has been an honor of a lifetime to serve this wonderful community and our patients, and we could not have accomplished all we have without the support and partnership of our board and staff,” Cotterell said in a statement.