Some UN peacekeeping operations are generally regarded as a success, e.g. El Salvador, Sierra Leone and Mozambique. Other missions are seen as obvious failures, such as Rwanda and Somalia. Not only do these mixed results justify research into the question “do peacekeeping operations actually contribute to durable peace?”, but both academic scholars and policy makers also try to identify factors explaining these differences. In earlier research, factors for success and failure were distilled from literature to explain the differing contributions of UN peacekeeping operations. After further research on the cases of Rwanda, Mozambique, El Salvador and Cambodia nine factors for success and failure were identified. According to these nine factors the probability that a peacekeeping operation makes a positive contribution to durable peace increases if: 1) the parties are sincere and willing to cooperate with the implementation of the operation; 2) the operation is able to provide a sufficient sense of security to the parties; 3) the operation has sufficient attention to the causes of the conflict both in depth and in breadth; 4) the operation receives co-operation from important outside actors and parties; 5) the operation is deployed timely and at the right time; 6) the operation is implemented by competent personnel under competent leadership, and with clear command structures; 7) the operation is part of a long term approach; 8) the ‘policy tools’ implemented in the operation are coordinated within the operation, as well as externally; and 9) the operation provides ‘ownership’. The questions addressed in this paper are: a) to what extent does UNMIS meet these different factors for success and failure for UN peacekeeping operations?; and b) to what extent does this picture match the image that results from a review of the North-South conflict and peace process, the role of UNMIS, and an analysis of the extent of durable peace? The answers to these two questions allow more insight into the chances for success or failure of UNMIS and provide further knowledge on factors for success and failure of UN peacekeeping operations.