This report analyzes the value of a Project Management Office (PMO) in sustainable programme and portfolio management. It begins with an overview of how a PMO can maximize and sustain organizational value through functions such as shaping decisions, strategic management, and organizational learning. The report further explores best practices in programme and portfolio management, emphasizing the importance of aligning business and strategic elements and defining performance evaluation criteria. A case study illustrates how a Fortune 500 IT organization leveraged a PMO to improve strategic initiative execution and resource management. Finally, the report identifies the antecedents of achieving sustainable value from a PMO, including governance, standardization, capability development, and execution. It emphasizes the PMO's role as a critical change agent and its importance in strategic alignment and operational sponsorship. References include Hobbs and Aubry (2010), Hurt and Thomas (2009), and Müller, Glückler and Aubry (2013).