In 1992 he was adopted into the Miniconjou band of the Lakota Nation. He is a graduate of St. Andrew’s School, in Delaware, the setting for
Dead Poets Society, and has degrees from the University of Delaware and the Writers’ Workshop of the University of Iowa. McCullough's most recent books of poetry are
Walking Backwards,
Sicomoro Oropéndola (a Spanish translation published in Colombia), and
Broken Gates (Red Dragonfly Press), and a book of stories,
Left Hand.
He has received numerous awards for his poetry including the Academy of American Poets Award, a National Endowment for the Arts Fellowship, a Pablo Neruda Award, a Galway Kinnell Poetry Prize, the New Millennium Poetry Award, the Blue Light Book Award and the Capricorn Book Award. McCullough has worked closely with Cambodian poet U Sam Oeur, survivor of the Pol Pot regime, and together they have published a bilingual edition of U’s poetry, Sacred Vows, and a memoir, Crossing Three Wildernesses.