After he volunteered for a Catholic service group, the St. Vincent de Paul Society, his eyes were opened to the poverty around him.

In the Austin community of Montopolis, Treviño partnered with a local Catholic priest, Father Underwood, to operate a VISTA (Volunteers in Service to America) program that had been newly created as part of the War on Poverty initiative.

[5] In the early 1970s, Treviño, Gus Garcia, Richard Moya and Gonzalo Barrientos were known by journalists as the "Young Turks" or the "Brown Machine".

These Hispanic leaders, along with a coalition that included labor activists, African-Americans, and young voters, overturned the traditional Anglo businessmen based power structure of Austin.

He established a review of hiring practices to provide fair access to city jobs for minorities and women.