A national questionnaire survey of 1,413 principals of middle-level schools (those offering any combination of grades 5 through 9) gathered data on principals' personal and professional traits, tasks, problems, and opinions on selected educational issues; on school programs; and on student, school, staff, and community characteristics. The data are presented in 151 text tables and 53 added appendix tables along with a narrative description and a concluding chapter that gives summary profiles of the principals and the programs. Included among the variables are (1) principals' age, sex, ethnic group, job history and experience, education, salary, tenure, professional and civic participation, career aspirations, work week, job responsibilities, authority, and self-fulfillment; (2) the community's geographic region, population, parental involvement, and pressure groups; (3) staff size, training, and pupil-teacher ratio; (4) school enrollment, per-pupil expenditure, grade level and organization, facilities, public or private status, program subjects, courses, student ability grouping, sports, extracurricular activities, and gifted programs; and (5) principals' attitudes on individualized promotion, student competency testing, extramural sports, grade organizational structure, enrollment size, teacher characteristics and effectiveness, administrative tenure, and needed types of preservice courses. Copies of the survey's two questionnaires are appended. (Author/RW)