Born in Whitewater, Wisconsin, he was raised in Plymouth, Michigan. He wanted to be a singer as a small child, but switched to acting when his voice changed. Within a month of moving to New York City, he became the understudy for Peter Firth in the Broadway production of Equus. He was nominated for a Tony Award for A Few Good Men.
His first film role was in the James Dean influenced film 9/30/55 in 1977. His next was in the highly popular National Lampoon's Animal House. In 1984 he was nominated for the Academy Award for Best Actor for his performance of Mozart in Amadeus, losing to his Amadeus co-star, F. Murray Abraham. Other films include Dominick and Eugene, Parenthood, Those Lips, Those Eyes, Echo Park and Mary Shelley's Frankenstein, and Slamdance.