This essay seeks to give philosophical expression to the vitality, willfullness, and recalcitrance possessed by nonhuman entities and forces. It also considers the ethico-political import of an enhanced awareness of “thing-power.” Drawing from Lucretius, Spinoza, Gilles Deleuze, Bruno Latour, and others, it describes a materialism of lively matter, to be placed in conversation with the historical materialism of Marx and the body materialism of feminist and cultural studies. Thing-power materialism is a speculative onto-story, an admittedly presumptuous attempt to depict the nonhumanity that flows around and through humans. The essay concludes with a preliminary discussion of the ecological implications of thing-power.