The REPAIR project is the first systematic historical study of repair practices, networks and infrastructures in the short 20th century (c. 1918-1990). Within the context of this emerging topic in the field of the history of technology, the project will analyse the changes and continuities in the history of maintenance and repair, using Luxembourg as a key example of a Western consumer society. REPAIR questions the prevailing master narrative of the emergence of a consumer society and concomitant decline of repair, helping to better understand when and how people care for the technologies they routinely use and thereby highlighting the hidden importance of maintenance and repair. By taking into account the long-term development of maintenance and repair, and their different historical trajectories, e.g. during economic and societal crises, the project will show that repair and self-repair has not become obsolete in modern consumer societies, but has remained integral to their economic functioning. REPAIR encompasses three research strands: the first investigates the maintenance and repair of one of the quintessential 20th century consumer technologies: the telephone; the second traces the decline of professional repair services in Luxembourg, using Luxembourg City and Esch-sur-Alzette as case studies; and the third focuses on the development of post-war self-repair practices, situated between leisure activity and political activism. Analysing the maintenance of technical infrastructures, urban repair offers and cultures of self-repair will advance our historical knowledge of the large material, organisational, knowledge and discursive investments needed to keep technologies functioning. By revealing when, why and how technical objects were maintained, repaired or scrapped, the project will provide crucial insights into the historical and political contexts of the emergence of consumer identities, the hidden societal and environmental dimensions of repair, and the quest for more sustainable consumption practices. REPAIR will thus contribute to one of CORE’s main objectives: the development of a sustainable social and economic system.