Mixed-blood and Filipino-born, Phillips was raised in Arlington, Texas, where he began acting at age 10. After receiving his college degree in theater, he studied film technique with Adam Roarke at the Film Actor's Lab in Dallas. Between 1983 and 1986 he worked at the Lab as an assistant director and instructor. Concurrently, he performed in several plays in Dallas and Fort Worth, including Doctor Faustus and Hamlet. From 1983-87 Phillips appeared in several small, independent, Texas-made films, beginning with Angel Alley; one of these, Trespasses (1987), he co-wrote, while he associate-produced another, Dakota (1988). His big break came when director Luis Valdez was casting the Hollywood biopic La Bamba (1987), which focused on early rock 'n' roller Ritchie Valens. Someone suggested Phillips for the role of Valens' brother, but after he auditioned he was selected by Valdez to play the lead. The film was surprisingly successful and Philips married its assistant director, Julie Cypher. With his performance as a barrio boy in Stand and Deliver (1988) he further established himself as a leading Hispanic star and representative of the Hispanic community. After playing an American Indian in the youth Western Young Guns (1988), he found himself fascinated with Indian culture and became a Cherokee blood brother. He wrote one of his films, Ambition (1991).