Relationship Development Intervention (RDI) is a research-based treatment program developed by Dr. Steven E. Gutstein. Whereas ABA aims to teach social skills directly, RDI focuses on building the "dynamic intelligence" that underlies the acquisition of those social skills in neurotypical children. It also focuses on the building blocks of motivation by developing episodic memory (seen as impaired in autism) and filling it with the child's own personal stories of competence and mastery. RDI emphasizes declarative (as opposed to imperative) communication, and aims for an appropriate balance of verbal and nonverbal communication.
Dr. Gutstein claims that 70% of his patients improved their ADOS score within 18 months, which is unprecedented (it was previously thought that improvement on the ADOS was impossible), and that a similar proportion are able to enter school without a shadow teacher or other personal assistant.