Internet integration in high schools on a schoolwide scale was examined through case studies of five high schools in inner city, urban, suburban, and rural communities across the United States. A total of 322 teachers, 19 administrators, 19 counselors, 7 technology coordinators, and 3,822 students were surveyed, and 219 staff and students were interviewed. Teachers at all the sites and across all subjects found the materials available to them on the Internet useful in their teaching. Once initiated, Internet use in the schools gave rise to an array of continuing resource demands. Internet availability in schools broadened opportunities for teachers and students, with the identified Internet-induced changes in schools ranging from infusing enhancements and complexities into existing arrangements and practices to fundamental shifts. As a transformative agent, the Internet equalized opportunities, changed student learning, changed social status, and changed the following aspects of teaching-learning systems: curriculum; teaching practices; teachers' and students' roles and relationships; and planning and management. The following contextual influences on schools' Internet integration were identified: commitment and leadership; interpersonal climate; access, time, competing priorities, training, and support; shared responsibility; and crises. Thirteen recommendations were presented. (Thirty tables/figures and 100 references are included. The staff and student survey questionnaire formats and interview protocols are appended.) (MN)