The Center for the Study of Evaluation at the University of California, Los Angeles, collaborated with school site personnel in an attempt to build an on-going, comprehensive, school-based information system useful in instructional decision making and general school renewal. Conducted at a suburban senior high school over an 18-month period, the project built onto the CASA (Computerized Accountability for Student Achievement) system already in use at the school. The information system idea interacted with three types of contextual factors: the school's social organization, teachers' thinking and reasoning about information, and leadership and support. While faculty opinion was divided as to the usefulness of a school-based information system (citing irrelevance of building-level data to ongoing classroom teaching and individual diagnostic information needs, as well as possible abuses such as biasing teacher attitudes), teachers' positive reactions seemed to center on the Student-At-A-Glance and Class-At-A-Glance data report forms. Without settings for use beyond the individual teacher in a self-contained classroom and without the principal's commitment, there seemed little likelihood of further development of the system at this school. However, information gathered during this project was used at both the classroom and building levels. (25 references) (DB)