Contemporary forms of infrastructural development herald alternative futures through their incorporation of digital technologies, mobile capital, international politics and the promises and fears of enhanced connectivity. In tandem with increasing concerns about climate change and the anthropocene, there is further an urgency around contemporary infrastructural provision: a concern about its fragility, and an awareness that these connective, relational systems significantly shape both local and planetary futures in ways that we need to understand more clearly. Offering a rich set of empirically detailed and conceptually sophisticated studies of infrastructural systems and experiments, present and past, contributors to this volume address both the transformative potential of infrastructural systems and their stasis. Covering infrastructural figures; their ontologies, epistemologies, classifications and politics, and spanning development, urban, energy, environmental and information infrastructures, the chapters explore both the promises and failures of infrastructure. Tracing the experimental histories of a wide range of infrastructures and documenting their variable outcomes, the volume offers a unique set of analytical perspectives on contemporary infrastructural complications. These studies bring a systematic empirical and analytical attention to human worlds as they intersect with more-than-human worlds, whether technological or biological.