Director of National Gallery Steps Down : Art: J. Carter Brown says he is resigning after 22 years to devote time to his children and other organizations. He hopes to leave by end of the year.

J. Carter Brown has resigned after 22 years as director of the National Gallery of Art in Washington.

In a letter released Friday, Brown, 57, said it is time for the gallery to have “fresh leadership” and that it has become difficult to divide his time fairly among his work with various organizations and his family responsibilities.

“Since the death of my parents (Anne Seddon Brown and John Nicholas Brown), I have been increasingly involved at Brown University in my native Providence, taking my father’s place on the Committee of Management of the John Carter Brown Library,” Brown wrote. “The John Nicholas Brown Center for the Study of American Civilization, of which I am a trustee and officer, will begin programmatic operations early next year.”

His great-great-great-grandfather, Nicholas Brown, founded the university in 1764 as Rhode Island College.

Brown also cited plans to continue as chairman of the U.S. Commission of Fine Arts, chairman of the jury of the Pritzker Architectural Prize competition and as a board or committee member of several other organizations, including the National Geographic Society, the John F. Kennedy Center for the Performing Arts, the American Federation of Arts and the American Academy in Rome.

But “of the highest importance,” Brown wrote, is his goal to devote more time to his two children, Elissa, 14, and Jay, 8. Brown and his ex-wife, Pamela Braga, recently reached a joint-custody agreement.

“One of the great benefits of having started so young at the National Gallery is being able to retire relatively early and in good health, when I can give time to other organizations that I am devoted to,” Brown said in a telephone interview. “And having married late, I can have the joy of spending time with my children while they are still young.”

“It makes me and my fellow trustees enormously sad to think of Carter Brown as no longer being director of this, the nation’s gallery,” said Franklin D. Murphy, chairman of the National Gallery’s board of trustees and chairman emeritus of Times Mirror Co., the parent company of The Times.

Brown said he has agreed to remain at his post until a successor is named by a search committee that has been formed by Murphy, but he added that he hopes to leave by the end of the year.

Brown joined the National Gallery in 1961, at the age of 26, and rapidly climbed to the museum’s highest position. He was appointed assistant director in 1964, deputy director in 1968 and director the following year, at the age of 34.

During his tenure, the gallery’s annual budget grew from $3.2 million to $52.3 million and its endowment increased from $34 million to $186 million. Annual attendance escalated from 1.3 million to 7 million. About 20,000 works of art were added to the collection under his administration.

Looking back over his career, Brown said the high point was the 1978 opening of the gallery’s East Building, designed by I.M. Pei. “After all those years of planning, to see the scaffolding come down and the building suddenly look so empty and dead, and then fill with people was an extraordinary experience,” he said.

The organization’s 50th anniversary, celebrated last year with a bonanza of gifts to the gallery, was unusually taxing but satisfying, he said. “We reinstalled the entire permanent collection, which was a feat in itself, not to mention the 50th anniversary celebration and putting together the exhibition ‘Circa 1492: Art in the Age of Exploration,’ ” he said.

The massive exhibition, representing a spectrum of creative arts from the time of Christopher Columbus’ voyage, closed last week.