Descartes’s mechanistic style of explanation in terms of extension, figure, and motion, and his austere substance-mode ontology, seems to leave no room for powers in the corporeal world. Yet, his natural philosophy grants a central role to forces as powers causing motion. In this chapter, I will situate Descartes’s conception of forces in the corporeal world within his broader account of powers. On a first approach, Descartes seems to divide powers into active, mental powers, conceived according to a cognitive model, and a reductionist model of physical powers mere spatial arrangements of bodily parts. Against this, I defend the view that Descartes is committed to forces as real tendencies in bodies : genuine modes which are distinct from their particular extension and motion, although presupposing them. Such tendencies constitute a third model for powers.