This article elaborates the relational ontology in an ethnographic study. The aim is to seek relational construction of preschool practice and how children's positions are constructed in it. The study is based on the understanding that ethnography and relational sociology share the idea that society emerges through repeated relations. The ontological thinking of relational sociology is applied in a micro-level analysis of three episodes from a Finnish preschool. We propose that relations appear in every single ethnographical episode and that carefully analysed repetitive relations can reveal a stabilised organisational structure. The analysis shows how the position of one child is structuring and being structured in everyday actions in a preschool. We argue that through relational analysis of ethnographic data, it is possible to seek sociological knowledge of institutions -- in this case, of preschool.