After graduating, BS returned to New York City, where he worked at a variety of jobs, including Head Start teacher, psychiatric aid, and carpenter. But in 1968, he moved to Stannard, VT, a tiny town, because he was "captivated by rural life." He worked as a carpenter, filmmaker, and writer. He created and sold "radical film strips" and other such stuff to schools, and he wrote for the alternative publication The Vermont Freeman. In the mid-1970's, he moved to Chittenden County.
He started electoral politics in 1971 as a member of the Liberty Union Party, an offshoot of the antiwar movement. He ran for governor in 1972 (1.1%) and 1976 (6.1%), and for US senator in 1972 (2.2%) and 1974 (4.1%).
In 1977, he quit and worked as a writer, then director, of the American People's Historical Society. While in it, he made a 30-minute documentary about labor leader Eugene Debs. He ran for President five times in the Socialist Party.
He then decided to run for mayor of Burlington, VT, and in 1981, he won by 10 votes with 43.4% of the vote. He slammed his main opponent, incumbent mayor Gordon "Gordie" Paquette, as being closely associated with a shopping-mall developer. He won again in 1983 with 52.1% of the vote, in 1985 with 56.1%, and in 1987 with 55.9%. In 1986, he ran for governor, losing with 14.4% of the vote. During this time, he called himself a socialist. In 1989, he decided not to run again, becoming a lecturer in political science in Harvard University, and in 1991, in Howard University.
As mayor, BS lead some downtown revitalization projects, like redeveloping the waterfront area into a mixed-use district with housing, parks, and public spaces. He criticized US foreign policy in Latin America, and he praised Noam Chomsky as "a very vocal and important voice in the wilderness of intellectual life in America" saying that he was "delighted to welcome a person who I think we're all very proud of." He also hosted an produced a public-access TV program, "Bernie Speaks with the Community", from 1986 to 1988. In 1987, US News & World Report ranked BS as one of the US's best mayors.
In 1988, BS ran for the US House of Representatives, but he lost with 37.5% of the vote. He tried again in 1990, winning with 56.0%, in 1992, with 57.8%, in 1994, with 49.9%, in 1996, with 55.2%, in 1998, with 63.4%, in 2000, with 69.2%, in 2002, with 64.2%, and in 2004 with 76.2%. A good winning margin.
He alienated members of both parties by arguing that they mostly worked for the rich, but over the years he had more roll-call amendments passed than any of his colleagues. He co-founded the Congressional Progressive Caucus in 1991.
He voted against some gun-control laws, though he voted for others, but he also voted against the Patriot Act and involvement in Iraq.