Cross-sectional findings in form of performance profiles of 71 severely language disturbed children three to ten years old corroborate the hypothesis that beside disturbances of complex performances, such as language, disturbances of earlier developmental performances mainly of the sensory-motor level can be observed. The prerequisites of these complex and of sensory-motor performances include different levels of perceptual integration. In each of the prefil constellation a different type of perceptual dysfunction can be observed: auditory dysfunction, or tactile-kinesthetic, or intermodal, or serial dysfunction. 15 children with intermodal and 8 with serial problems were exposed to therapy for several years. The therapy attempted to stimulate the disturbed perceptual processes. Longitudinal observations demonstrated that progress became first apparent in more primitive performances, and secondly, with a time lag, in more complex performances. These findings not only confirm the original hypothesis that in these children language disturbances are secondary to perceptual disturbances, but demonstrate also the possibility of early diagnosis and treatment of children with language difficulties.