The chapter presents the invasive methods of preoperative diagnostics and neurosurgery for language-related brain mapping. The focus is on the investigation of naming and language processing with intracranial electrodes during neurosurgical procedures on awake patients. The focus is on both the recording of electrical brain activity and the electrical stimulation of cortical brain regions during neurosurgery. Specific language-related findings from studies with cortical electrodes and implanted depth electrodes will be presented. In addition, important findings from short-term anesthesia of one hemisphere (Wada test) and short-term lesioning of cortical areas using an external magnetic field (TMS) in relation to language processing are explained. The various results of brain mapping for the cortical representation of language will be discussed.