In 1965, UCLA recruited Dr. George Tarjan, a pioneer in mental retardation research, to build a combined research and clinical program in intellectual and developmental disabilities. We received one of the first MRRC (Mental Retardation Research Center) building grants from the State of California to the Neuropsychiatric Institute which added the top five floors to the NPI (now Semel Building), dedicating that space to IDD-related research. Dr. Tarjan was the founder of both the University Center for Excellence in Developmental Disabilities, named in his honor, and the MRRC, now called the IDDRC. The mandates for these centers were: (1) The acquisition of new knowledge about mental retardation and human development, (2) The development of a research program characterized by a high degree of collaboration between basic and clinical scientists and including both biomedical and behavioral research and (3) The training of new investigators in research involving mental retardation and developmental disabilities. In 1970, the first MRRC funds from NICHD were authorized by Congress. UCLA became one of the original 12 sites and has been continually funded since then. The State of California provided additional funds to secure permanent faculty positions for MRRC scientists, funding that continues today. The MRRC made formative contributions to the basic science of neurodevelopment with NICHD funding. As examples, seminal work on the role of glia in neurodevelopment was an early accomplishment of the IDDRC. Dr. Jean de Vellis, who pioneered this work, became the IDDRC director in 1994 and served for over two decades in that role. Dr. Susan Bookheimer was named Director in 2014, with Dr. Harley Kornblum as Associate Director.