The paper recounts the background of Wyatt v Stickney, which resulted in a landmark decision establishing a constitutional right to treatment for mentally retarded persons. Events which triggered the Wyatt litigation include an employee action brought about by staff in an effort to obtain re-employment. The involvement of the American Association on Mental Deficiency in the case is discussed, and testimony of AAMD's then-president is excerpted. Court rulings in the case, the appointment of a master, and promulgation of standards comprising minimum constitutional requirements for adequate habilitation of the mentally retarded are described. Subsequent reopening of the case to determine compliance is said to have focused on the guarantee of habilitation rather than merely an enriched environment. Further court action in the case is summarized, and changes in the state facility organization, institutional population, per diem expenses, and staff to resident ratios are noted. (CL)