Social play has long been considered a key context for exploring children’s early social relationships, with substantial research exploring children’s interactions with parents and peers. As part of social play, children use verbal and non-verbal communication strategies to create a shared experience with the play partner. These strategies help play partners to build intersubjectivity, or a shared understanding of the play, together. The present thesis builds on this body of research by focusing on how children engage in shared interactions and the influences on these interactions. Over three studies, it explores social play in the context of children’s early relationships, concentrating on the social processes at work when children play with a partner.

Using a multi-method approach, where the first study employs qualitative methods and the latter two studies apply quantitative methods, this thesis explores children’s early play across activities by investigating fathers’ experiences of intersubjective interactions with their infants and analysing individual, group, and activity influences on intersubjective communication with peers in early childhood. Across these studies, results show the importance of intersubjectivity for social play and the wide social influences on intersubjective communication in children’s play. Through reflexive thematic analysis of qualitative interviews in Study 1, fathers of 6- to 24-month-olds were found to enjoy bonding during interactions with their infants and preferred activities they felt served a purpose. In Study 2, multi-level modelling of secondary data showed substantial dyadic effects on 6- to 7-year-old children’s intersubjective communication. Building on the results of Study 2 using the same sample, Study 3 reveals interaction effects between dyadic characteristics and activity context on this communication, where the relationship between play partners predicted communication differently across two activities.

Together, these findings show the importance of social influences on children’s play with others, including how social play is experienced and how it manifests. They also suggest that viewing social play through an intersubjective lens can inform social theories of play. By exploring social play across play partners and activity contexts, this thesis provides a conceptual basis for understanding the influences on social play and how social play can be researched beyond previous attention to children’s individual characteristics.