Teachers' interrelations with the principal, subject coordinators, and homeroom teachers in a high school have tightened significantly as a result of the computerization of the school's instruction-administration subsystem. Changes were found in six major categories: accountability, instruction evaluation, supervision, feedback, frequency of meetings, and shared decision making. Greater cooperation, mutual accountability, teamwork, joint planning, and mutual instruction evaluation and feedback developed among teachers teaching the same subject, but not between teachers teaching different subjects.