A two-part research and evaluation study was conducted to examine an elementary (K-8) school district's implementation of a computerized instructional management system, the "Computer-Managed Instruction/3000" (CMI), as a means of facilitating the assessment and updating of student mastery of 78 district-defined curricular objectives. The testing system consisted of a data bank of tests based on the district mathematics objectives, equipment to machine score student answer sheets, and reports detailing student mastery of the objectives. This system was piloted by administrators and teachers at four district-selected schools. A detailed interview schedule was developed to elicit such information as background in the district; knowledge of the CMI system, including how, why, and by whom it was selected; uses of the system for testing and instruction; technical problems; potential uses of the system; and its effects on school organization and instruction. Analysis of the responses of 49 school staff members--principals, resource teachers, teachers, and clerical staff from both pilot and nonpilot schools--revealed wide variation on all of the factors studied. The factors that appeared to be influential in the nature and degree of CMI implementation efforts at the individual school sites were identified as: (1) technical procedures and personnel; (2) focus on instructional uses; (3) key instructional personnel; (4) site climate and leadership; (5) training; and (6) attitudes and incentives. A consistent ordering of the four schools along these dimensions was found, and it is suggested that the patterns of successful implementation and use of the CMI system identified in this study can provide guidance to other school districts planning and implementing their own CMI systems. A coding matrix is appended and references are included. (DJR)