Harold DeRienzo began his career in community development in the early 1970s, co-founding the Banana Kelly Community Improvement Association in the South Bronx. At a time of widespread housing loss, they led efforts to preserve and redevelop affordable housing, helping establish the organization as a national model for self-help community development. From a staff of 6 and housing portfolio of 566 units in 2002, Banana Kelly currently has three offices, a housing portfolio of over 2,000 units, and a staff of about 40 employees, not counting building service employees. The organization transformed from within about a decade ago and restructured itself as a mutual housing association. As part of that change, Banana Kelly has a strong Residents Council, which appoints a plurality of board members. Harold served as Executive Director until 1982, continuing to live in the community for 35 years.

In 1982, Harry became Vice President/CEO, and later President, of the Parodneck Foundation for Self-Help Housing. They expanded the foundation’s focus on self-help and mutual aid, launching programs such as a home improvement initiative for seniors, a national effort to combat predatory lending, and the city’s first 197-a plan. He also grew the CATCH program, establishing over 800 units of resident-controlled housing in New York City.