In today?s volatile world, supply chains face unprecedented challenges from globalisation, digital disruption, sustainability pressures, and unexpected crises. While vertical collaboration between suppliers and buyers has received significant attention, horizontal cooperation ? collaboration between organisations at the same supply chain level ? offers a promising yet underutilised strategy for achieving operational and economic benefits in a turbulent environment. This book provides theoretical and conceptual analysis of horizontal cooperation in supply chains, grounded in current literature and enriched with models and real-world examples.Drawing on published empirical research and documented case-based evidence from transportation, retail, manufacturing, technology-intensive industries, and humanitarian supply chains, it explores collaboration evolution, clarifies what distinguishes horizontal cooperations, and systematises existing conceptualisations and typologies. Key topics include supply chain and transportation planning integration, coalition formation, and the governance and stability implications of cost and profit allocation mechanisms. The book critically examines governance challenges under competitive conditions, with particular attention to coalition stability, distributive mechanisms, and power asymmetries, bridging theoretical insights with practical implementation mechanisms.The book will interest academics and graduate students, as well as logistics professionals seeking to understand the strategic and operational potential of horizontal cooperation in contemporary supply chains.