This book examines the establishment of trust funds by States and international organizations in respect of international development, environmental protection, fiscal stabilization, democracy-building and others. It traces their foundational legal attributes, their investment potential and legal status as investors and the legal means by which they are set up, particularly treaties, resolutions of international organizations, informal agreement, memoranda of understanding, unilateral acts and others. The book examines the various decision-making and management models adopted in contemporary trusts, the fiduciary and other duties of the trustee, as well as the status and rights of beneficiaries. Moreover, it examines the personality of trusts funds, whether as mere accounts, informal associations, foundations under domestic law or even international organizations. Finally, the book discusses the potential of trust funds in enhancing participatory democracy, budgeting and governance, revenue sharing and fiscal management, as well as the role of environmental trust funds. A useful resource for international lawyers, academics and international organisations.