It has long been recognized that from the first months of life auditory perception plays a crucial role in speech and language development. Only in recent years, however, is the precise mechanism of auditory development and its interaction with the acquisition of speech and language beginning to be systematically revealed. This paper presents the results of a series of studies exploring the relevance of electrophysiological measurements for the objective diagnosis of children with language and speech disorders. In the "first", retrospective, study, an inventory was made of clinical neurological, neuropsychological, logopedic and neurophysiological findings obtained from 43 children referred to the Paediatric Neurology Centre for the diagnosis of their speech and language deficits. Neurophysiological abnormalities were found in 95% of these children, among these deviant auditory evoked potentials (AEVPs). The "second" study demonstrated developmental trends in the waveform of the cortical AEVPs up to age 6 years; the implications for longitudinal studies are discussed. Preliminary results from the "third" study show emerging differences in auditory event-related potentials (AERPs) for young children who are at risk for developmental dyslexia based on their family history. These findings underscore the clinical usefulness of neurophysiological measures for the diagnosis of speech-language disorders. Clinical protocols are further developed and tested.