Available Open Access digitally under CC-BY-NC-ND licence. Some of the largest quantities of data produced today occur as the result of experiments taking place at Big Science facilities.This book tells the story of a unique research journey following the people responsible for designing and implementing data management at a new Big Science facility, the European Spallation Source (ESS) in Lund, Sweden.It critically examines the idea of data as an absolute ‘truth’ and sheds light on the often underestimated, yet essential, contributions of these data experts.Providing a unique glimpse into the inner workings of Big Science, this book fills an important gap in science and technology studies and critical data studies.