To address the 15 hypotheses formulated for this research, several subject groups will be studied. The functional activation patterns of normal right-handed adults will be compared with normally developing right-handed children and adolescents (ages 6-17) during tasks involving speech segmentation (into phonemes) and speech formulation. All will be native speakers of American English without foreign language use in the home. Corresponding subject groups will be adults and children with stuttering or phonological processing disorders who are right-handed native speakers of American English. Our aim will be to determine how brain function for speech perception and production change during completion of the critical period for speech development and how these systems differ in children with disorders of speech control and phonology who continue to have problems during this period.