A lifetime resident of East Harlem, Hiram was 13 years old when he took up photography, urged on by a social worker who saw the youngster’s promise and sense of mission:   Hiram resented the stereotype of his people as impoverished and his neighborhood as crime- and drug-ridden.  He saw the beauty of his people, the strength of his community, and he wanted to show both in his photographs. He learned his craft by trial and error and refused to be dissuaded by jeers that there was no such thing as a Puerto Rican professional photographer.

In 1969, Hiram was one of the founders of the New York branch of the Young Lords Party, a Chicago-based group of Puerto Rican activists.  As the YLP’s official photographer, he documented the party’s major campaigns, among them the Garbage Offensive, the takeover of Lincoln Hospital in the Bronx, and the occupation of the First Spanish Methodist Church. After the YLP ceased operations, Hiram participated in the Nuyorican cultural awakening of the late 1960s and 70s, which saw the formation of the Center for Puerto Rican Studies at Hunter College, El Taller Boricua, and El Museo del Barrio. He served as director of El Museo from 1974 to 1977.

For decades Hiram stressed what he called “dignity over fame.”  Adamant about retaining control over his work, he rejected opportunities to exhibit it—except when he was persuaded by his friend Marta Moreno Vega, director of the Caribbean Cultural Center, to participate in the exhibition The Young Lords Party, 1969-1975, featuring his photos and text by his friend and fellow Young Lord Felipe Luciano. It would be some 30 years before he would consent to lending his work to another major exhibition.

In preparation for its 30^th anniversary in 2005, El Centro and the Museum of the City of New York partnered on El Barrio:  Puerto Rican New York, the first exhibition mounted at a major museum in New York City to explore the emergence of El Barrio as the incubator and touchstone of the New York Puerto Rican identity.  Hiram served as consulting curator and contributed a significant number of his works to the exhibition.

Hiram was proud not to have a presence on the Internet until his son Pablo and daughter Alita persuaded him otherwise. Gradually, he began to let the world in.  A decade after El Barrio: Puerto Rican New York, his work was simultaneously in Anchor at the Hunter East Harlem Gallery and in Presente! The Young Lords in El Barrio at both the Bronx Museum of the Arts and El Museo del Barrio. Two years later, his photographs could be seen in the exhibition Down These Mean Streets at the Smithsonian American Art Museum in Washington, D.C., and later at El Museo del Barrio.

By 2021, his large format photographs were displayed near sites of significance to the YLP in East Harlem in Mapping Resistance:  The Young Lords in El Barrio, a public art project organized by Miguel Luciano, whom Hiram had mentored. His work was featured in Greater New York at MoMA PS 1, in Activist New York at the Museum of the City of New York, and at Binghamton University Art Museum in Joy, Play and Resistance in the work of Miguel Luciano and Hiram Maristany.  He was in conversation with several museums that were planning to acquire or exhibit his work.

It is tragic that Hiram died before he could enjoy the many honors that awaited him.  But he knew that they were going to happen, and he also knew that he alone would have a place in history as the most consistent photo documentarian of his beloved community.