The choice of an information system is a critical factor of success in an organization’s performance, since, by involving multiple decision-makers, with often conflicting objectives, and having several alternatives with aggressive marketing makes for particularly complex decision-making in terms of choice by consensus. The main objective of this work is to create an analysis and selection method for an information system designed to support school management, pedagogical and administrative components, using a multi-criteria decision aid system – MMASSITI – Multi-criteria Methodology to Support the Selection of Information Systems/Information Technologies. It integrates a multi-criteria model that seeks to provide a systematic approach to the process of choice of information systems, able to meet sustained recommendations concerning decision and scope. Its application to a case study has identified relevant factors in the selection process of school educational and management information system and how to gain a solution that allows the decision maker to compare the quality of the various alternatives.