One of the nation’s largest and most innovative affordable housing developers, The Community Builders (TCB) has long been a reflection of Patrick Clancy.

He joined the organization while still an idealistic Harvard Law School student in 1971 and has led the organization since 1976. After more than 40 years and nearly 30,000 homes, Clancy will retire as president and CEO at the end of the year.

“I’ve been very lucky to be able to do the work I love,” he said.

COO Bart Mitchell has been selected to take over the top post in January.

Boston-based TCB has a presence in 14 states and contributes more than 1,000 new housing units a year. More than that, the organization has been a leader in comprehensive neighborhood revitalization projects across the nation, developing mixed-income neighborhoods and connecting residents with valuable services.

For Clancy, housing has been a platform to help families move out of poverty.

While a student at Holy Cross College in Worcester, Mass., he volunteered to work at a settlement house. “I saw kids with the deck stacked against them and decided that I wanted to try to be useful to the poor and marginalized in this society,” he said. “I was a ‘60s radical, if you will. I went to law school to get a tool.”

He was soon organizing tenants and suing slumlords. However, he was more comfortable controlling outcomes than trying to force others to change their behavior. He moved from an advocacy role to developing housing, which turned out to be a strong fit.

While still in law school, he did the first nonprofit affordable housing tax shelter syndication in the country to rehab row houses in the south end of Boston.

Clancy was awarded Holy Cross’ Sanctae Crucis Award in 2004 for his lifetime contribution to improving urban neighborhoods.

After leaving TCB, he plans to travel with his wife, Mary Jane, and spend more time with their children and grandchildren. Clancy has also been helping Holy Cross students turn their interest in social justice into careers much like he did.