San Pedro came from a family with musical roots and he became his career early. When he was still young, he succeeded his deceased grandfather as the local church organist. By then, he had already composed songs, hymns and two complete masses for voices and orchestra. After studying with several prominent musicians in the Philippines, he took advanced composition training with Bernard Wagenaar of the Netherlands. He also studied harmony and orchestration under Vittorio Giannini and took classes at Juilliard in 1947.

His other vocation was teaching. He has taught at the Ateneo de Manila University, virtually all the major music conservatories in Manila^{[citation needed]}, and at the College of Music of the University of the Philippines, Diliman, where he retired as a full professor in 1978. He later received the title professor emeritus from the university in 1979.^[5] He also became a faculty member of the Centro Escolar University Conservatory of Music in Manila. San Pedro was known for composing the official march of Makati.^{[citation needed]}

On May 9, 1991, President Corazon C. Aquino proclaimed San Pedro a National Artist of the Philippines for Music.^[5]

He married Gertrudes San Pedro with whom he had five children: Rhodora, Bienvenido, María Conchita, María Cristina and Lucio, Jr.

San Pedro died of cardiac arrest on March 31, 2002, in Angono, Rizal, at the age of 89.^[1] Many peers from the Order of National Artists attended his tribute at the Tanghalang Pambansa, including: Napoleon Abueva, Daisy Avellana, Leonor Goquingco, Nick Joaquín, Arturo Luz, José Maceda, and Andrea Veneración. He is buried in his hometown of Angono, Rizal.

San Pedro's works include a great variety of musical forms ranging from band music, concertos for violin and orchestra, choral works, cantatas, chamber music, and songs for solo voice. He also served as a conductor of many Filipino bands such as Peng Kong Grand Mason Concert Band, the San Pedro Band of Angono, and the Banda Angono Numero Uno.^[4]

Major Works

• The Devil's Bridge

• Malakas at Maganda Overture

• Lulay

• Sa Ugoy ng Duyan (with the collaboration of Levi Celerio)^[1]

• Dance of the Fairies
• Lahing Kayumanggi

Compositional Philosophy

San Pedro is known for advocating "creative nationalism" when composing his own music. According to him, representing Filipino identity doesn't just fall from literally using the material from folk songs but rather getting the most important essence,style and common touch of being a Filipino. A good example of his "creative nationalism" was his "Lahing Kayumanggi" where he dedicated this piece to "the heroic struggle of the Filipino people for liberation from colonization."

I have always attempted to immortalize the virtues and aspirations of the masses whom I believe are the pillars of the nation. I have placed them on a pedestal for everyone to emulate, and putting them on a pedestal is not an easy task. I want them to be revered, and, as such, the manner of emulating them cannot be done through a vulgar approach, but rather through utmost creativity.^[6]