This research describes the rules and ways of forming playgroups in the children's peer culture. The data were obtained through observation by videoing children's activities in various play situations. The data were analysed through ethnographic thick description by using microanalysis and participation framework. The analysis was focused on who could participate in play and what kind of behaviours inhibit participation. In addition, children's actions in order to get in play activities were observed as a part of the children's peer culture. To become included, four various methods were noticed: (1) Prowling the play activities; (2) Nonverbal communication; (3) Abstaining from critiquing; and (4) Showing enthusiasm and worming one's way to play with a toy. Furthermore, tattlers, emotionally incompetent, or dominating children were not accepted in play activities. This research provides information and increases understanding about children's behaviours and how to guide their emotional skills development.