A prolific American science fiction writer, he is best known for his 1987 novel, When Gravity Falls. His other works include What Entropy Means to Me (1972) and Felicia (1976).
He published several stories in the Clarion anthology in the early 1970s. His debut novel, What Entropy Means to Me, was a finalist for the prestigious Nebula Award.
He did not drive a car for the majority of his life.
He was born and raised in Cleveland, Ohio. He was married three times; his third wife was fellow science fiction writer Barbara Hambly.
He and Jo Walton were both Nebula Award nominees.