The ecological technique selected and modified for use with residential juvenile treatment homes was one that focuses on the environment of behavior, collects transducer as opposed to operator data, examines molar rather than molecular behaviors, and relies on naturalistic observation. The study was conducted in 11 residential treatment homes in middle class neighborhoods in Tucson, Ariz. Three of the residences housed female delinquents; eight were for male youths. Residing in each home were house parents with four to seven students ranging in age from 11 to 21 years. Four homes had an all-Indian population; seven were mixed. A total of 121 behavior settings (molar behaviors, events, activities, happenings, programs, functions, etc. which occur with regularity in specific locations) were identified, with 38 regarded as needed and between 57 to 83 found to exist in each home. Questionnaires were developed on 25 ecological variables with respect to 1 behavior setting at a time. The data from all the behavior settings within a home were considered together for the evaluation of the environment. The development and testing of this instrument accomplished the main purpose of this research. Additional pursuits involved testing the validity of the interview method and the reliability and validity of the ecological technique, as well as its cross-cultural validity. Also developed and applied in one home over a 6-week period for 14 selected ecological variables and 4 behavior settings. Comparisons were made of sexually, racially, and administratively different homes. High ecological scores indicated a positive educational-therapeutic climate and the success of a home. The study yielded a set of environmental design guidelines recommending that such homes be located in developed residential neighborhoods within easy access of schools and other community and commercial centers. An inside area of 2,000 square feet is desirable, with one parent bedroom and bathroom in addition to other mandatory amenities, a common living area as a focal point, separation of quiet and noisy areas, and privacy for private behaviors. Tabular data are included. Study instruments and forms are appended.