Measuring Information System success is an important issue for both researchers and practitioners. Evaluating success helps managers in assessing MIS performance and in improving MIS function. Several measures of MIS success were proposed in the past [DeLone and McLean, 1992]. What is even more important for MIS managers and researchers is the set of independent variables that affect the success of MIS. The factors that affect MIS success can be related to organization, individual, and technology. There are numerous studies in the past on MIS success factors, but they consider either technical issues or behavioral/managerial issues and not both. In this research, we take a comprehensive look at the factors in determining critical variables. We considered both these factors in our model to predict MIS success. Our research will highlight critical success variables (whether internal or external, whether technical or managerial/behavioral) that influence the success of MIS. Thus, the objectives of our research are: i) to identify the independent variables from past models, which could affect the success of MIS. ii) to find the dimensions of these variables which represent the success of MIS, by using factor analysis. iii) to build a model for success of MIS project, which identifies most critical variables. iv) to predict the success of MIS projects based on these critical factors.