Much has been written about predictive mechanisms supporting perception, language, and action. This contrasts with a sparseness of studies reporting brain measures that directly reflect specific aspects of prediction. The present talk shows recent EEG studies on a brain correlate of prediction, the Prediction Potential (PP), a slow negative shift observed before the onset of linguistic and non-linguistic stimuli and before the onset of actions that can be predicted from their context. These data shed new light on the neural mechanisms involved in predictive processing, particularly about where semantic, perceptual, and action predictions originate and when and where these predictions influence perceptual and semantic processing after stimulus presentation. I will discuss these data considering existing theories of language processing and how the PP may be of interest to future neurocognitive research on predictive processing.