This volume is one of several which describe the characteristics, quality, and costs of services to severely handicapped children and youth in 100 providers across the nation. This volume includes the development of data collection instruments and a mail survey of potential providers of services to severely handicapped children and youth. The survey was conducted for the purpose of creating a pool of providers from which 100 facilities could be selected for site visits. From the 1,550 respondents to the mail survey, 100 providers were selected who serve severely handicapped clients aged 21 or under. This selection was accomplished by grouping the respondents into eight sampling categories according to the number of clients they served. Providers were also selected based upon whether they served a majority of clients who are either severely mentally retarded, severely emotionally disturbed, severely multiply handicapped, or deaf-blind. Some providers were selected who served a mixed severely handicapped population. The volume contains discussions of the procedures and methodology used in conducting the study; characteristics of the 100 providers; client observations; costs of services; the relationship of expenditure and quality; a summary of major findings; and specific policy questions and suggestions based on the present data base and/or the expertise of project staff. (RC)