This article initiates a conversation on how contemporary Eastern European peripheralization and the hegemony of the energy transition impact social struggles, introducing the concept of "Periphery in Movement." Through the examination of Serbia's anti-extractivist movement against the mining corporation Rio Tinto, we ground this concept through three core specificities. The first is the power imbalance positioning the movement in opposition to corporate interests, the European Union, and national elites. The second is the conflictual convergence of civil actors, who have undergone significant ideological and practical transformations from the Yugoslav Wars to the present. The third specificity is the "how" of Periphery in Movement and its new political propositionalities and potentials. Periphery in Movement expands beyond traditional civil society and social movement studies by addressing struggles at the Eastern European periphery that build propositional and life-preserving resistance.