As mayor, Anderson rose to nationwide prominence as a champion of several national and international causes, including climate protection, immigration reform, restorative criminal justice, LGBT rights, and an end to the "war on drugs". Before and after the invasion by the U.S. of Iraq in 2003, Anderson was a leading opponent of the invasion and occupation of Iraq and related human rights abuses. Anderson was the only mayor of a major U.S. city who advocated for the impeachment of President George W. Bush, which he did in many venues throughout the United States.

During his years as Mayor, Rocky successfully fought many important battles, including victories for mass transit, wise long-term growth planning, greater respect toward and legal protections for minority communities (including equal benefits for gays and lesbians and their partners), and for unprecedented youth programs. He successfully challenged the state’s English-Only law and opposed grandstanding Homeland Security campaigns against immigrant workers in the nation’s airports.