Attempts to develop a ‘municipal science’ bear witness to the challenges posed by the city to methods of government in the first decades of the twentieth century, particularly in France. Both in France and on the international scene, reformers sought new ways of thinking ‘scientifically’ about towns and their government. This article takes a serious look at ‘municipal science’, a fragile development which was never fully accepted in academic circles. It studies the endeavours to provide a scientific clothing for the reforming discourse developed by associations of town councillors and disseminated by teaching institutions or journals devoted to municipal administration. It also examines the contribution made by this crusade – at once political and scientific – to the renewal of public action through local authorities.