Roberto Sierra was born in Vega Baja, Puerto Rico, on October 9, 1953. His musical education was thorough and extensive, with studies first at the Puerto Rico Conservatory (1969-1976), the University of Puerto Rico (1976-1979), the Royal College of Music in London and London University (1976-1978), Utrecht-based Institute for Sonology (1978-1979), and finally the Hamburg Hochschule für Musik (1979-1982), where he both studied and worked with Ligeti.
Following his studies Sierra returned to Puerto Rico and wrote the choral work Cantos populares (1983), and there soon followed his watershed work Júbilo (1985). Meanwhile, he supported himself by working in two educational administrative posts (1982-1989): Director of Cultural Activities at Puerto Rico University and Chancellor of the Puerto Rico Conservatory of Music.
In 1989 Sierra, still tasting the success from the Milwaukee Symphony Orchestra's North American premiere of Júbilo, was named composer-in-residence of the MSO, serving until 1992. He joined the faculty at Cornell University in 1992, where he remains today as the chair of the music department. Throughout the 1990s Sierra received numerous prestigious commissions, including a joint one from the Pittsburgh, West Virginia, and Utah Symphony Orchestras, which resulted in the Violin Concerto Evocaciones (1994). Other notable works came from his prolific pen, including the percussion concerto Con madera, metal y cuero (1998). The sensational successful of Missa Latina at its 2006 premiere led to further performances, including at the 2007 Casals Festival in Puerto Rico. Naxos released a recording of it in 2009, with Andreas Delfs leading the MSO. He was a finalist for the 2008 Pulitzer Prize for his Concerto for Viola.