Relations between neighbours represent informal social relations that constitute a part of everyday life for virtually all individuals in contemporary urban societies. While aspects of neighbour relations have been studied in connection with research on local communities, gentrification, and neighbourhood effects, little research focusing specifically on interactions between neighbours has been conducted and theoretical reflection on the central concepts remains lacking. This article attempts to fill this research gap by developing a theoretical framework for the sociological understanding and investigation of neighbour relations. The research material used consists of previous studies on neighbour relations. The method for the task was analysis of concepts coupled with theoretical reasoning based on a review and a synthesis of relevant previous research. Familiar concepts like ‘neighbour’, ‘neighbouring’, and ‘neighbourliness’ are scrutinised, deconstructed, and redefined, noting that there are often two perspectives on each: the experiences of residents and those of outside observers. Various sociological aspects of neighbour relations are discussed, including neighbour relations as an acquaintance relation, neighbour relations as the basis of a community, and the cultural content of the neighbour role. A model of levels of neighbourly interaction is presented.