The project investigated the effectiveness of an evironmental therapy training program for geriatric mental health workers when used in two different institutional settings. Site A was a State-operated facility for psychiatric in-patient care, accommodating 2,000 patients, with emphasis on maintenance and general patient welfare. Site B, a former State-operated custodial care facility with 100 beds, placed emphasis on diagnosis and assessment for subsequent placement in nursing/boarding residences and patients' homes. Thirty trainees at each institution were selected non-randomly by the institutional directors for the training program promoting patient independence. The first training phase consisted of the presentation of environmental therapy principles in 18 two-hour sessions (lecture, discussion, role playing, audiovisual materials, and small group problem-solving sessions). Two pre- and post-measures, a Negative Attitude Toward Old Age Score and an Assessment of Hospital Score, were used at both institutions. The results of pre/post comparison on the Assessment of Hospital Score showed significant differences, demonstrating the effectiveness of the training program in changing trainees' assessments of direct patient care and of their hospital environment in general. The principles of milieu therapy appear to be sufficiently useful to institutional geriatric service providers to warrant continued dissemination. (EA)