Steven Stucky, a Pulitzer Prize-winning American composer whose work was widely commissioned by major orchestras around the world and who earned respect as a conductor, teacher and author, died on Sunday at his home in Ithaca, N.Y. He was 66.

The cause was an aggressive form of brain cancer that was diagnosed in November, his wife, Kristen Frey Stucky, said.

In 2012, Mr. Stucky provided some revealing insight into his own music with an offhand comment before the New York premiere of his Symphony. “Graspable” is the way he described the 20-minute, single-movement piece in conversation with Alan Gilbert, conductor of the New York Philharmonic before the performance. For all the modernist complexities of Mr. Stucky’s scores, his music was sanguine, lucid and structurally clear — graspable in the best sense.

Symphony, jointly commissioned by the Los Angeles and New York Philharmonics, goes through dramatic contrasts, from stretches of gnashing intensity with hurtling rhythmic bursts to passages of harmonically tart yet hymnal calm, and even a jittery, slicing scherzo. Yet, despite the teeming shifts, the narrative design and overall thrust of the piece come through vividly.