Within Terrorism Studies, Rapoport, D. C.’s (2004. The Four Waves of Modern Terrorism. In A. Cronin, & J. Ludes (Eds.), Attacking Terrorism: Elements of a Grand Strategy (pp. 47–65). Washington, DC: Georgetown University Press.) Wave Theory is a theoretical landmark that covers modern terrorism since 1880. However, this masterpiece neglects Eco-Terrorism, a phenomenon starred by the Animal Liberation Front (ALF), the Earth Liberation Front (ELF) and some other ideologically similar organizations. Even though it has been catching authorities’ attention around the world, such negligence towards the phenomenon has been replicated by others working on Rapoport's Wave Theory, leaving a question unaddressed: ‘Was/Is there an ‘Eco-Terrorist Wave’?’ Methodologically built upon a Time Series analysis on the Global Terrorism Database (GTD) (1970–2017), the present research harmonizes Eco-Terrorism under Rapoport's Wave Theory. Based on the evidence collected, the phenomenon has been evolving in a Rapoportian ‘Wave-Like’ pattern since 1972.