Baer was born in Geneva, New York, in 1948. He was raised in the Bronx and Wayne, New Jersey, and he's a graduate of Rutgers (B.A. English) and New York University (M.A. English). He completed his doctoral dissertation in English at the University of South Carolina under the direction of James Dickey and then attended the Johns Hopkins' Writing Seminars (M.A. Creative Writing) where he studied with John Barth and David St. John. He later attended the University of Southern California's Graduate School of Cinema (M.A. Cinema) where he received the Jack Nicholson Screenwriting Award. He currently holds the Melvin M. Peterson Chair in English and American Literature at the University of Evansville in southern Indiana. A Roman Catholic, Baer lives with his wife and two children in Evansville, Indiana.

Baer is the author of five books of poetry, including The Unfortunates, recipient of the T.S. Eliot Poetry Prize, and "Bocage" and Other Sonnets, recipient of the X. J. Kennedy Poetry Prize. His other books include translations from the Portuguese, Luís de Camões: Selected Sonnets; the textbook, Writing Metrical Poetry; and four collections of interviews, including Classic American Films: Conversations with the Screenwriters.

In 1989, William Baer was the Founding Editor of The Formalist (1990-2004), a small poetry journal which played a significant role in the Formalist poetry revival (New Formalism) and published the work of seven Nobelists and fifteen Pulitzer recipients. He’s also the former poetry editor and film critic for Crisis Magazine. Currently, he serves as the founding director of the St. Robert Southwell Institute, the director of the University of Evansville Press, the contributing editor at Measure, the faculty director of The Evansville Review, and the director of the Richard Wilbur Poetry Series, the Howard Nemerov Sonnet Award, and the Willis Barnstone Translation Prize.

As a playwright, Baer's full-length plays (The Amistad Case, Guiteau, and Lighthouse, recipient of the James H. Wilson Playwriting Award) as well as his shorter plays have been produced at numerous American theaters, including the Dayton Playhouse in Dayton, Ohio; Acrosstown Repertory Theatre in Gainesville, Florida; the Florence Little Theatre in Florence, South Carolina; Playwrights' Circle in Palm Springs, California; the Fells Point Theater in Baltimore, Maryland; the Edward Albee Last Frontier Theater Conference in Valdez, Alaska; the Metropolitan Playhouse of New York in New York City; the Camino Real Playhouse in San Juan Capistrano, California (awarded "Best Play in the Festival"); Emerging Artists Theatre in New York City; the Chicago Dramatists Theatre in Chicago; Masker's Theater, Belfast, Maine; and the St. Tammany One-Act Play Festival in Covington, LA.