Recent research demonstrates that one in five school districts is under pressure to purge objectionable books from its libraries and classrooms. This paper briefly summarizes literature and court decisions dealing with censorship in the schools and describes a study of censorship in Illinois schools. In the study, a 68-item questionnaire asked 200 high school principals to rate the amount and origin of censorship in the areas of teaching methods and textbook content and to identify persons responsible for selecting textbooks and library materials. The findings indicate that, while many potential items have never been a concern in the schools surveyed, controversial films and TV programs are censored most often. The highest percentage of textbooks censored were English texts, while Communism and controversial issues receive most censorship in social studies texts and sex education ranks highest among topics censored in health and science tests. Censorship originates from a wide community base, according to the study, including parents, religious groups, and local organizations. Textbook selection is made most often by teacher committees, and library materials are selected most often by librarians and teachers. (JEH)