Alan Percy, M.D., Child Neurology, presented the inaugural Bengt Hagberg Memorial lecture at the annual Swedish Neuropediatric Society meeting in Stockholm, Sweden, on Thursday, January 21st at the Swedish Society of Medicine, Svenska Läkarsällskapet. Dr. Hagberg was a renowned child neurologist who is credited with establishing child neurology in Sweden, creating training programs both for child neurologists and neuropediatricians in Sweden, and making seminal contributions to our current understanding of static encephalopathy (cerebral palsy), neonatal hydrocephalus, and a number of neurodevelopmental and neurodegenerative disorders including Krabbe disease, metachromatic leukodystrophy, and Rett syndrome. Dr. Hagberg died in the Spring of 2015. This lecture acknowledges his illustrious career.In the late 1950's, Dr. Hagberg recognized this unique neurodevelopmental disorder at approximately the same time as Dr. Andreas Rett did so in Vienna, Austria. After discussions with other child neurologists in Europe, Hagberg published what was to be the first widely circulated English-language publication on Rett syndrome. Following a chance meeting with Dr. Rett in 1981, he determined the disorder should be called Rett syndrome. Dr. Percy, first met Dr. Hagberg in 1964 while working in the laboratory of Lars Svennerholm in Gothenburg, Sweden as a medical student, and then re-connected with him again in 1984 following publication of the initial report on Rett syndrome in the Annals of Neurology in 1983. They collaborated closely over the following nearly thirty years to advance understanding of this disorder, occurring largely in females, and now known to be due to mutations in the methyl-CpG-binding protein 2 (MECP2) gene. Dr. Percy has led an NIH-funded study since 2003 that has greatly expanded knowledge of the natural history of this disorder and encouraged the development of current clinical trials.