This article discusses the ways in which a group of four-year-old children co-constructed friendship networks when they began primary school in Wales, UK. This discussion has emanated from a wider study of the everyday social interactions children engage in when new to their school environment. The children’s interactions were investigated through the use of an inductive, ethnomethodological approach through the combination of conversation analysis (CA) and membership categorization analysis (MCA). The transcriptions revealed that the children used the collective pro-terms ‘we’ and ‘us’ in order to explicate affiliations and exclusions with their peers in their everyday social interactions. These findings offer an insight into the daily social organization processes children engage in and suggests their preference for exclusive dyadic friendships. The article also reveals the social competencies which four-year-old children have in accomplishing social organization.