The role of immigration in the life of the late medieval and early modern town was important. A key part of this process (and best captured in the sources of urban origin) was the integration of a new burgher into existing urban social and economic structures. Like most of the power-economic relations of this time, the individual-burgher relationship to the group was based on mutual guarantees confirmed by an oath taken by a newly-accepted member. The essay will focus on the relevance and usability of early modern and modern codifications of urban oaths to explore the development of urban structures in the late Middle Ages and Early Modernity. It will also focus on comparing the content of the oath of the new burgher both in the general context of the oaths used in the urban environment and in the context of the specific development of the urban community in the area under consideration (Silesian and north Moravian towns based on Magdeburg rights) compared to the situation in the Western part of Holy Roman Empire.