Chapter 5 explores how the foundations for TNGO legitimacy have changed over time, creating imperatives for TNGOs to invest in new capabilities and adopt new practices. In the past, TNGOs derived legitimacy from their espoused principles, representational claims, elite expertise, demonstrated financial stewardship, commitment to charity, and patterns of conformity. More recently, TNGOs themselves have helped to bring about a shift toward new bases for legitimacy that focus on effectiveness, strategy, leadership, governance, transparency, and responsiveness. However, transitioning to the legitimacy practices of the future is complicated by the persistence of an antiquated architecture that still demands that TNGO conform to legacy expectations. Nevertheless, new approaches to enhancing legitimacy provide a wide range of opportunities that invite organizations to proactively align their aspirations with emerging stakeholder expectations.