The Baylor Rett syndrome (RS) program project has enrolled more than 60 of the anticipated 70 children to be evaluated over 5 years. The program is composed of 6 individual projects and a Core center for coordinating the evaluations and managing the data. The projects consist of I) Clinical assessment of RS; II) Status of communication skills in RS; III) Clinical neurophysiology and sleep in RS; IV) Epidemiology of RS; V) Molecular genetics in RS; and VI) Neuropathology of RS. This program project and a similar program at the Johns Hopkins University School of Medicine are complementary. © 1990, All rights reserved.