Our research relates to the relations between municipalities, ironmasters and central power during the initial phase of the process of industrialisation (1870-1914) and ensuing urban development. This topic will be studied through a series of questions, to which the archives will try to give answers. The originality of this research lies in the fact that the question of the industrialisation is analysed under aspects which differ from those usually covered by Luxembourgish historiography, especially the impact of municipal finances on the relationship between local authorities and ironmasters. The study concludes that the rhythm of industrialisation of a municipality and the management of related impacts varies according to the degree of interaction between municipal authorities and ironmasters, which depends on a certain number of factors: the state of municipal finances following the settlement of steel factories, the nationality of the leaders of the factories, the weight of employers' paternalism, and finally, the socio-professional composition of the municipal bodies. The study also shows that the governmental authorities are reluctant to intervene in the relationship between municipal bodies and ironmasters, for fear they could offend Luxembourg's main providers of wealth. The study also shows that the government's involvement remains limited to specific cases.