Junior and junior-senior high schools enroll a large proportion of our early adolescent population. The programs they provide, the services they offer, their administrative practices, and the character of their staffs have far-reaching effects. These programs, services, practices, and staff characteristics constitute the scope of the present survey, the first of its extent and coverage to be conducted on a nationwide basis. The study is a sampling drawn from a universe of 4,549 junior high schools with 75 or more pupils, and 7,841 junior-senior high schools with more than 125 pupils. Of the total of 1,507 questionnaires mailed to principals, returns were received from 1,360. The report provides information on the study and the background of the junior high school, and discusses: (1) Administrative arrangements--double and staggered sessions, length of the school year, length of the school day, and number and length of class periods; (2) organization for instruction--grouping of pupils in class sections, block-time classes and unified learning experiences, homeroom and activity periods, provisions for study during the school day, library services, and availability of audiovisual equipment; (3) pupil evaluation, orientation, and services--tests and inventories, promotions, policies for marking pupils, progress reports, guidance counselors, cumulative record files, health, and articulation with lower and upper grades; (4) curriculum--required and elective subjects, and extraclass [cocurricular] activities; and (5) staff--professional supervisory and specialist personnel, and teachers. This study tends to indicate that, in general, size has more to do with differences in educational practices at the junior high school level than does the type of school. Appended are a description of the sample design and the questionnaire used in the survey. (Contains 12 footnotes and 47 tables.) [Best copy available has been provided.]