In 1976, Mazur started a series of paintings and pastels based on visits to the Stoneham Zoo in Massachusetts, which was in a derelict state at the time. In the Stoneham Zoo series (1976 - 1979), Mazur explored the subject of captivity, a theme which recurred throughout his career. In his work, Mazur addressed society’s role in exploitative policies and systems of confinement. In a 1993 interview with the Archives of American Art, Mazur said, "I decided to do some work on the monkey cages at Stoneham Zoo, which were very depressed. Telling the story of captured animals became important."