William Rubin, 78, curator at Museum of Modern Art

NEW YORK -- William Rubin, who as director of painting and sculpture at the Museum of Modern Art played a central role in shaping the museum's collections and exhibitions, has died.

Mr. Rubin, whose health had been declining for some time, died at his suburban Pound Ridge home on Sunday, the museum said. He was 78.

Mr. Rubin joined the museum in 1967 and was named chief curator of the painting and sculpture collection a year later. Among the many influential exhibitions he organized was a Picasso retrospective in 1980 that filled the entire museum. ''Pablo Picasso: A Retrospective," MoMa said, was one of the most important and successful exhibitions in the museum's history.

Other exhibitions launched by Mr. Rubin included ''Picasso and Braque: Pioneering Cubism," ''Frank Stella: Works From 1970 to 1987," ''Primitivism in 20th Century Art: Affinity of the Tribal and the Modern," ''Cezanne: The Late Work," and ''Dada, Surrealism, and Their Heritage."

An art historian and curator, Mr. Rubin's tenacious pursuit of the art he believed MoMA should own resulted in his greatly expanding the museum's holdings in abstract expressionism with works such as Jackson Pollock's ''One: Number 31, 1950" and Barnett Newman's 1950-51 ''Vir Heroicus Sublimis," and the work of contemporary artists like Anthony Caro and Stella.

His acquisitions for the museum also included Picasso's ''Guitar," a metal construction sculpture from 1912-13 that the artist gave to Mr. Rubin as a donation in the south of France.

He leaves his wife, Phyllis Hattis; and a daughter and two brothers.