Gallegos was born in San Antonio, Texas, but raised in Portland, Oregon, where his parents relocated during World War II to work in the city's shipyards.

[2] As a young adult, he also worked in the shipyards before serving one year in the U.S. Air Force and three years with the Oregon Air National Guard during the Vietnam War.

[2] After completing his military service, Gallegos earned his BS in psychology and his master's degree in social work from Portland State University, and his PhD from the University of Denver.

[2] In 1982, he helped create a minority social work curriculum at the University of Washington before becoming a professor at San Diego State University, where he served on the faculty from 1983 to 1988.

[2] From 1990 to 2010, Gallegos served on the board directors of the Catholic Charities in Portland.