Summarizes the efforts of RT-315 to describe the current state of practice in mega-project delivery, rank the root causes of poor mega-project performance, and identify any needed changes in planning and execution practices to improve performance. Explains how the research team identified 34 impact factors, prioritizing the most likely factors and the ones with the most negative impacts on mega-project outcomes. Also discusses how the team identified specific case examples of these negative impacts, and how it developed mitigation strategies and recommendations. Introduces the Mega-Project Assessment of Criticality Tool (MPACT), a resource that incorporates these findings into a Microsoft® Excel-based tool and implementation guide. NOTE: Actual tool included with IR315-2.