This survey identifies the characteristics that set the middle school apart from other types of academic organization. A questionnaire was sent to 1,988 schools whose names included the words "middle school," as well as to other schools that could conceivably be considered middle schools. Stratified random samples of 275 elementary and 91 junior high schools were added to furnish a basis for comparing middle schools with non-middle schools. Tables show (1) number, location by USOE regions, grades included, enrollment, and grades taught by various types of schools; (2) ratios of pupils to counselors, teachers, and administrators by grade and enrollment; (3) types of class schedules and study provisions, kinds of athletic programs and social activities, and primary responsibility for discipline by grade organization. The middle school philosophy is to prepare pupils for adult responsibilities withou exposing them prematurely to experiences for which they are unprepared. Although less than half the respondents believe that their schools are maximally implementing this philosophy, a larger proportion believe that their schools are attempting to do so. A bibliography is included. A related document is ED 024 121. (MFL)