Elliott Carter, Composer of the Avant-Garde, Dies at 103 James Estrin/The New York Times Elliott Carter, working on a score in his apartment in Greenwich Village in 1996. He won two Pulitzer Prizes. Elliott Carter, the American composer whose kaleidoscopic, rigorously organized works established him as one of the most important and enduring voices in contemporary music, died on Monday in Manhattan. He was 103 and had continued to compose into his 11th decade, completing his last piece in August. His death was announced by Virgil Blackwell, his personal assistant. Mr. Carter died in his Greenwich Village apartment, which he and his wife bought in 1945 and where he had lived ever since. Mr. Carter's music, which brought him dozens of awards, including two Pulitzer Prizes, could seem harmonically brash and melodically sharp-edged on the first hearing, but it often yielded drama and lyricism on better acquaintance. And though complexity and structural logic were hallmarks of his works, the music he composed in the decade leading up to his widely celebrated centenary, in 2008, was often more lyrical, if not necessarily softer at the edges. Mr. Carter, a protégé of the American modernist Charles Ives, acknowledged that his works could seem incomprehensible to listeners who were not grounded in the developments of 20th-century music. Even trained musicians sometimes regarded his constructions as too difficult to grasp without intensive study. Yet he had many advocates among players, and his works were frequently performed and recorded. "As a young man, I harbored the populist idea of writing for the public," he once explained to an interviewer who asked him why he had chosen to write such difficult music. I learned that the public didn't care. So I decided to write for myself. Since then, people have gotten interested. Mr. Carter never lacked for commissions from major orchestras, soloists and chamber groups, and late in life he was able to impose conditions on those who sought his works. He refused to be held to deadlines, saying he would release his compositions when he felt they were ready. And for many years he would not accept commissions from orchestras that had not played his earlier music. Long before he began enforcing that rule, however, many of Mr. Carter's works had found their way into the active repertory. In the mid-1980s, he observed that hardly a year went by without at least one New York performance of his Double Concerto for Harpsichord and Piano With Two Chamber Orchestras (1961). His Cello Sonata (1948) is considered one of this century's finest additions to that instrument's repertory, and his solo keyboard works, the Piano Sonata (1946) and "Night Fantasies" (1980), are performed regularly and have been recorded several times. Mr. Carter continued to explore new ground into his later years. He avoided opera for most of his career because, as he put it in 1978, "American opera is a novelty, to be played once and that's all, even when they're good pieces," and because he doubted he could find a libretto that interested him. Yet when he was 90 he completed his first opera, "What Next?" The opera, with a Dadaistic libretto by Paul Griffiths, a former music critic for The New York Times, had its premiere in 1999 at the Berlin Staatsoper Unter den Linden, with Daniel Barenboim conducting. It had its American premiere in a concert version at Carnegie Hall in 2000 and its first staged performance in the United States at Tanglewood in 2006 - an event filmed and released on DVD. As Mr. Carter's centenary neared, the frequency with which his music could be heard only increased, making it clear that for at least two generations of young performers, even his thorniest works held little terror. In the summer of 2008, for example, the entire Festival of Contemporary Music at the Tanglewood Music Center was devoted to Mr. Carter's work, with performances of dozens of pieces from every stage of his career (including several premieres). Mr. Carter attended most of the concerts. There were many such tributes that year, and the attention unnerved him, he said. "It's a little bit frightening, because I'm not used to being appreciated," he said in an onstage interview at Zankel Hall the night after a celebration with the Boston Symphony Orchestra. So when I am, I think I've made a mistake. Despite his years, he remained vital almost until the end. His last composition, "12 Short Epigrams," a piano work for Pierre-Laurent Aimard, was completed on Aug. 13. Another piece, "Instances," for Ludovic Morlot and the Seattle Symphony (commissioned with the Tanglewood Music Center), was completed in April. In June, in what Steve Smith, writing in The Times, called a "miracle of continuing miracles," the New York Philharmonic performed the premiere of "Two Controversies and a Conversation." Mr. Smith called it a "pocket-size double concerto." "The applause for Mr. Carter, wheelchair bound but characteristically animated," Mr. Smith wrote, "resounded thunderously." Elliott Cook Carter Jr. was born in Manhattan on Dec. 11, 1908, the son of a wealthy lace importer. While he was a student at the Horace Mann School, he wrote an admiring letter to Ives, a New Englander with a crusty manner who nevertheless responded and urged him to pursue his interest in music. When Mr. Carter attended Harvard, starting in 1927, Ives took him under his wing and made sure he went to the Boston Symphony Orchestra concerts conducted by Serge Koussevitzky, who programmed contemporary works frequently.