The European Union, Africa, and the ACP States provides a comprehensive account of how the Samoa Agreement - governing relations between the European Union (EU) and the Organisation of African, Caribbean, and Pacific States (OACPS) from 2024 to 2044 - was negotiated. By explaining how more than one hundred countries, operating under markedly unequal conditions, forged a complex and politically sensitive accord on a range of issues, including development, trade, human rights, security, environmental sustainability, and migration, it makes three main contributions to scholarly and policy debates. Conceptually, the book advances the notion of deliberative negotiation under constraints, showing how justificatory reasoning and strategic bargaining interact in international treaty-making: rather than treating power and persuasion as opposing logics, it demonstrates how negotiators use both while navigating domestic political pressures, institutional mandates, and evolving geopolitical conditions. Empirically, the volume benefits from unprecedented access to internal processes - direct participation in preparatory and negotiating rounds, extensive documentary evidence and a broad corpus of elite interviews - which together open the black box of international negotiations and reveal how positions were crafted, defended, and adjusted, offering a level of process insight rarely available in studies of contemporary diplomacy. Substantively, it situates the Samoa Agreement not only in the context of the evolving ACP-EU partnership but also within broader transformations in North-South relations, highlighting how persistent tensions shaped negotiation behaviour and continue to affect implementation.