Born in Salinas, Puerto Rico, William Oritz was raised in New York City. He studied composition at the Conservatory of Music of Puerto Rico under Héctor Campos Parsi and Amaury Veray. He holds a master’s degree from SUNY at Stony Brook (1976), where his professors included Billy Jim Layton and Bülent Arel, and a PhD from SUNY at Buffalo (1983), where Lejaren Hiller and Morton Feldman were his professors. Ortiz served as assistant director of Black Mountain College II, NY, also teaching composition and music theory at the school. He has held the position of chair of the department of humanities and has served as band conductor for the University of Puerto Rico at Bayamón. As a music critic he has contributed to The San Juan Star.

Among his many works Oritz has completed commissions for the Casals Festival, the Guitar Society of Toronto, the Puerto Rico Symphony Orchestra, and the New York State Council of the Arts. His approach to composition is characterized by an eclectic adoption of popular and urban music genres as part of his compositional palette. Early on he incorporated elements from urban street music, found mostly in the Latino and Black neighbourhoods of New York City and in the poorer neighbourhoods of San Juan, as reflected in Street Music (1980), Graffiti Nuyorican (1983), De Barrio Obrero a la Quince (1986), and Bolero and Hip-Hop en Myrtle Avenue (1986).