This book explores formations of oceanic kinship in transnational American literature and culture from the seventeenth to the twenty-first centuries. The chapters in this edited volume examine how kinship as a critical idiom and conceptual lens can help us rethink forms of human and nonhuman belonging in oceanic contexts. The book's notion of kinship encompasses practices of mutual care which emerge from an understanding of interdependence, collectivity, and affiliation. Taken together, the essays critically engage with a variety of themes and concepts in oceanic studies: postcolonial ecologies, maritime labor histories, slavery and indentured servitude, extractive capitalism, settler colonialism, race and ethnicity, gender, sexuality, the posthuman, the Anthropocene, and decolonial epistemologies. They therefore contribute new perspectives from kinship studies to current conversations in the blue humanities and adjacent fields such as diaspora studies, Black studies, Indigenous studies, ecocriticism, and queer theory. Together, they probe possibilities for an oceanic ethics of care for the twenty-first century. This book will be relevant to students and scholars of oceanic studies, literary studies, cultural studies, and those interested in the intersections of kinship, the environmental humanities, and postcolonial theory. The chapters in this book were originally published as a special issue of Atlantic Studies.