This study originates from the recognition that project management research is replete with normative theories on what need projects to be successful. However, it has performed worse with respect to assisting the understanding of how and why similar projects do not have similar performances during their life-cycles. It claims that the poor performance of major infrastructure projects, acknowledged by cost overruns and scheduling delays, is due to their lack of resilience when confronted with critical events that are inherent in their life-cycle. Therefore, it addresses the overarching question: How do projects cope with the critical events that occur at some point in their life-cycle? And why and how are some troubled projects able to maintain positive adjustments (cope successfully) while others cannot? By addressing these questions, the first goal of this study is to reveal the "resilience enablers". These are factors and conditions enabling the successful coping process (maintaining performance after the critical event) in projects confronted with unexpected events. The second goal is to translate the new knowledge of "resilience enablers" into recommendations for practitioners to enable them to actually make use of the insight into a troubled project's behavior. To study these questions, a qualitative research design was developed. It is articulated on the exploratory case study of one of the most important infrastructure project of this century. The result consists of two sets of findings, both relate to the critical events' managements and the factors and conditions that enabled the project's resilience. This thesis contributes to project management research with a middle range theory. The project performance can be seen and explained from a new and original perspective of project resilience. It also contributes to the project's management practice with recommendations aiming to help project actors to 1) identify and assess the resilience of their project organization, along with the identification and management of the risks. And to 2) maintain project system performance after the critical event through continuous adoption of risk-focused, and protection-focused strategies, which imply uncostly measures that enable project resilience.