Although abundant evidence demonstrates that play is the source of development for preschool-aged children in various cultures, few studies have investigated the role of adult-children collective play in supporting the development of children in institutional care settings. This study examined whether and how a play-based programme created developmental opportunities for children in an orphanage in China. The focus child, Shanshan (pseudonym), three years and seven months old, was observed in the natural setting of an orphanage. Relevant to this paper, digital video observations and fieldnotes were used for data collection. The cultural-historical concepts of play and the social situation of child development were used to analyse how Shanshan changed through a ten-week intervention. Findings suggest that even within a short period of time, the implementation of collective play changed the social situation for the child in institutional care, and had considerable impact on the child's play development and engagement. This study contributes to understanding how collective play can act as an effective intervention strategy for children in institutional care.