In 1994, Jack Hamilton pointed out evidence of Somerville’s surging multiculturalism to a Globe columnist.

“Over here, there’s a traditional Irish bar, where they throw darts,’’ he began. “Then there’s a Greek restaurant. And then a Middle East restaurant, but it’s really an Armenian restaurant. Across from that, in the old firehouse, is the Portuguese elderly center. And where we are is a Greek-owned insurance agency that services Haitians, Brazilians, and Hispanics.’’

On and on he went. Mr. Hamilton, whose career in human services included nearly 30 years as executive director of the Community Action Agency of Somerville, believed in celebrating his city’s diversity. In one of the city’s neighborhoods, he once counted 27 languages.

He also believed government should help ease the transition for recent immigrants, and told the Globe in 2008 that thanks to their presence, “Somerville has become a very exciting place to live.’’

Mr. Hamilton died of pneumonia Jan. 12 in Mount Auburn Hospital in Cambridge. He was 75 and had lived in Somerville most of his life.

Under his leadership, the agency known as CAAS ran a Head Start program and created a host of programs for poor people of all ages.

“Jack was hands-on in every sense,’’ said US Representative Michael Capuano, a Democrat from Somerville. “He never asked anybody to do a job he wouldn’t do himself.’’

During Mr. Hamilton’s tenure at CAAS, the agency’s budget grew significantly as it began offering education programs for Somerville residents, plus advice and assistance on issues including housing, health care, and employment.

Mr. Hamilton, who “would advocate for anything as long as he believed in it,’’ never shied away from politics, Capuano said. “He was very pragmatic, and he understood that politics was often the way to get from where you were to where you wanted to be.’’

A son of John Hamilton and the former Gertrude Norton, John W. Hamilton grew up “working class and very angry’’ in the Mission Hill housing projects, he told the Globe in 2008.

Later, he channeled that anger into antipoverty work. He worked for youth and mental health agencies before joining CAAS in 1983.

But first he became a Catholic priest. Mr. Hamilton attended Mount St. Alphonsus seminary in Esopus, N.Y., and received a master’s in theology from St. Mary’s College in North East,Pa.

After he was ordained, he was sent to a small city in Brazil and he learned to speak Portuguese. He became disillusioned, however, by what he saw as the church’s preference for the wealthy donor class over the impoverished masses.

“The contrast was probably a bit too much for him to handle,’’ said his wife, Kate Cloud of Somerville, who said he was “very quiet when it came to helping people, but not so quiet when he was objecting to injustice.’’

Mr. Hamilton, who was known to all as Jack, left the priesthood after a few years and returned to the United States, where he worked in youth and mental health agencies before taking over CAAS and settling in Somerville. He met Cloud, who also worked in human services, in the mid-1970s. They were married by a Somerville justice of the peace in 1999.

Speaking Portuguese came in handy as he worked with Brazilians who dropped into CAAS. He also taught himself conversational Spanish and Haitian Creole, and some Punjabi, so he could chat with his Sikh neighbors.

“He was really interested in meeting people, and in communicating with them in their own language if he could,’’ his wife said.

In 2008, Mr. Hamilton told the Globe that “to have fun in Somerville, you have to speak at least two languages.’’

His longtime friend Lois Levinsky of Somerville, who worked for Mr. Hamilton in the 1970s, called him “a great boss with an amazing sense of humor.’’

“He was really inspirational to all of us who wanted to do the right thing and do it well, and make an impact on the community where we lived,’’ she said. “He was an important person.’’

Mr. Hamilton graduated with a second master’s degree, in public administration, from the Harvard Kennedy School. During his career, he received several awards for community activism.

Dorothy Kelly Gay, a former Somerville mayor who emigrated from the same town in Ireland as Mr. Hamilton’s parents, said he was “no shrinking violet’’ when arguing for funding for projects to better the lives of children, immigrants, tenants, and the disabled. “He laid it right on the table,’’ she said. “But he always had great plans for using the money he was asking for . . . who could say no to him?’’

Mr. Hamilton enjoyed baseball, reading, and hiking, often taking trips to the White Mountains, his wife said. Although he was “a real extrovert,’’ she added, he preferred dining at home to restaurants.

“He was very content to live a simple life in terms of creature comforts,’’ she said. “He didn’t require much.’’

A service has been held for Mr. Hamilton who, in addition to his wife, leaves a stepson, Josh O’Brien of Somerville; two brothers, Robert of Georgetown and Larry of Hudson; two sisters, Pat and Janice, both of West Roxbury; and two step-grandchildren.

“Jack was a voice for those who had no voice, and he befriended everybody,’’ Gay, the former mayor, said. “His wake was such a tribute to him, to see all those people there, so many of them immigrants. He gave them the hand up that set them on their way.’’

Mr. Hamilton told the Globe that when Somerville’s new Head Start building was named the Jack Hamilton Center it was “totally embarrassing’’ for him, and he insisted that a plaque inside also list the names of his colleagues.

“I can’t think of one thing — this is true — I’ve done by myself,’’ he said.

Kathleen McKenna can be reached at kmck66@verizon.net.