On September 19, 1995, The New York Times and The Washington Post submitted to “Unabomber” Theodore Kaczynski’s demand to publish his manifesto, a treatise that would come to be known as the “Unabomber Manifesto.” While Kaczynski has been serving a life sentence for the letter-bombing campaign that he perpetrated between 1979 and 1995, the radical environmentalist rhetoric contained within his manifesto has become available to an even wider audience of current and would-be environmental extremists than when it was first published. Given its availability online, the Unabomber Manifesto has become one of the most well-known rhetorical artifacts endorsing environmental extremism. Using Herbert Simons’ “rhetorical requirements” approach, this study demonstrates that the Unabomber Manifesto represents Kaczynski’s rhetorical efforts to animate like-minded environmental extremists. The article concludes by discussing how the Unabomber Manifesto resonated with some radical environmentalists and may have even served as a catalyst for later acts committed by U.S.-based environmental extremists. By utilizing a framework for examining the rhetoric of violent revolutionary social movements, this study provides further insight into what motivates environmental extremists of today.