Despite the application of project management tools and techniques in projects worldwide, still a large number of projects fail to meet their objectives. Based on studies on the history of failed projects, it is obvious that projects do not result in failure overnight. With hindsight, project managers are often able to point out the most likely factors leading to project failure. One approach towards prevention of project failure or deviation from the main goal is to attempt to detect possible signs of project failure in early stages of projects. These signs are referred to in the literature as Early Warning (EW) signs. The major challenge for the project managers is the identification of these signs and attempting to respond to them in order to prevent the negative circumstances. Although it is not a proven fact that identification of EW signals is a guarantee against project failure, there are a number of resources which consider paying attention to these signals and attempt to respond to them as a contribution to project success. This PhD dissertation provides better understanding of the EW phenomenon, possible approaches for identifying EW signs and barriers against effective responses to these signs in projects. In addition to contributing to existing project management research by increasing the understanding of the application of EW procedure in projects, the present research attempts to contribute to development of more effective approaches towards responding to EW signs of potential future problems in projects. Three research questions (RQs) guide the research: - RQ1: How are early warning detection approaches addressed in the existing literature? - RQ2: How can the utilization of early warning identification approaches improve project performance in practice? - RQ3: What are the possible barriers against effectively responding to early warning signs and how to enhance early responses to EW signs in projects? The research questions are addressed through seven corresponding publications, based on extant literature review within the EW field and other relevant areas, alongside four different case studies among various industries (Oil and gas, Telecommunication, Transportation and R&D) and a survey among Norwegian project managers or leaders in different industries. The main focus points in the seven individual publications which comprise the dissertation include: - Publication I: Investigation on possible EW identification approaches and their strengths and weaknesses - Publication II: Presentation of a conceptual framework for application of performance measurement as an EW identification approach (An analysis on the case of London Ambulance Service (LAS) project) - Publication III: Investigation on application of performance measurement as an EW system ( A case study on the Tyrihans project within the oil and gas industry) - Publication IV: Investigation on application of Project Health Check (PHC) as an EW system ( A case study on LTE and MOVE projects within the telecommunication industry) - Publication V: Investigation on how identification of EW signs in early stages of projects can aid project managers towards better decision making ( A case study on the Norwegian High Speed Railway (HSR) project within the transportation industry) - Publication VI: Investigation on behaviour of different filters against effective flow of information in international projects - Publication VII: Investigation on possible barriers against identifying and responding to EW signs and remedies for improving the EW procedure. A model is developed based on the findings from the individual publications and the initial literature studies, which illustrates a detailed EW …