This special issue of Pacific Historical Review, “Crossroads of Indo-Pacific Environmental Histories,” is guest edited by Gregory A. Barton and Brett M. Bennett. The special issue explores how environmental historians can use the concept of the Indo-Pacific to understand both the deep and contemporary histories of regions that are frequently viewed through Indian Ocean world or Pacific Ocean world perspectives. A preface and this introduction provide a theoretical overview, establishing some of the key temporal, spatial, and causal parameters of the Indo-Pacific. The following articles by Timothy P. Barnard, by Ruth Morgan, and by Gregory Barton and Brett Bennett highlight how local and foreign powers have sought to control the Indo-Pacific’s natural resources to shape new economies, ecologies, and polities within the region during the past two centuries. Broadly, the special issue encourages other historians to engage with the Indo-Pacific concept due to its theoretical depth as well as its relevance to contemporary geopolitical affairs.