He attended Shimer College from 1961 to 1965, then moved to Berkeley, California, where he took part in the countercultural and radical adventures of the 1960s.

Over the next few years, he taught himself French in order to read the original situationist writings (most of which were then unavailable in English) and made several extended visits to France to meet various situationist groups and individuals, as well as shorter trips to meet contacts in other European countries and in Japan and Hong Kong.

[4] In 1981, Knabb published the Situationist International Anthology, a large collection of articles drawn mostly from the French journal Internationale Situationniste.

Knabb's own writings include leaflets, comics, pamphlets and articles on Wilhelm Reich, Georges Brassens, Gary Snyder, the 1960s hip counterculture, the 1970 Polish revolt, the 1979 Iranian revolution, the 1991 Gulf War, the 2006 anti-CPE revolt in France, the 2011 Occupy movement, the 2016 Trump election, and the 2020 covid crisis.

Longer works include The Relevance of Rexroth (a study of the anarchist poet and essayist Kenneth Rexroth), Gateway to the Vast Realms (a reader's guide to 500 recommended books), and The Joy of Revolution (an examination of the pros and cons of diverse radical tactics followed by some speculations on how a nonstate and noncapitalist postrevolutionary society might function).