Peter Soyer Beagle was born in the Bronx, New York on April 29, 1939. He attended the University of Pittsburgh, receiving his Bachelor's degree at the age of nineteen in 1959, and from 1960 to 1961 he attended graduate school at Stanford University. He has lived much of his life since then in California. In 1964 he married Enid Elaine Nordeen; the couple had three children, divorcing in 1980. He is now married to Indian author and photographer Padma Hajmadi, and they are well-known habitues of the environs of Davis, California. Beagle was vice-chairman from 1968 to 1969 of the Santa Cruz chapter of the American Civil Liberties Union.

Beagle declares that "I don't write sequels," even though the novella Giant Bones and the other stories in the 1997 Giant Bones collection take place in the imaginary world of The Innkeeper's Song, and the novella Lal and Soukyan features characters from The Innkeeper's Song...