The RDI program was developed by the psychologist Steven Gutstein in the 1990s. Gutstein studied the means by which typical children become competent in the world of emotional relationships. He looked at the research in developmental psychology and found that early parent-infant interaction predicted later abilities in language, thinking and social development. Two books of RDI-based activities as well as a book explaining the background ideas were published in 2002, but RDI has changed significantly since then and is now only available through the RDI_LS, or learning system, accessed by trained consultants.