Many studies have shown that mental categories share processing mechanisms with perception and action. According to a strong view of grounded cognition, these sensory-motor mechanisms are sufficient for mental representations, while more moderate views might say that other, more abstract mechanisms also play a role. Several lines of research support the idea that mental categories are grounded in sensory-motor processes. Behavioral studies show interactions between cognition and perception or action, suggesting that they share mechanisms. Neuroscientific studies have collected evidence that sensory-motor brain areas are involved in cognition. Several connectionist models show how sensory-motor experiences can be combined and result in categorical representations. These findings suggest a highly flexible and interactive system in which the strict distinction between sensory-motor processing and other types of processing may no longer be relevant.