The report summarizes the first year of the Toddler Research and Intervention Project, a research program to devise and evaluate different aspects of educational intervention with children, ages 1-4 years, with moderate to severe development problems (primarily mental retardation). Described are the children who composed the intervention group, the physical classroom environment, classroom procedures, results of the first 8 months of intervention, initial investigations of language and cognitive training, and the parent training program. Also described are nine research projects carried out on the delayed and nondelayed young children involved, investigating such areas as effects of reinforcement schedules on acquisition of stimulus control, Piaget's object permanence concept, motor imitation, contingent social stimulation of vocalizations, discrimination learning, maternal teaching style assessment, classification skills, and receptive vocabulary skills and learning. (Author/KW)