The study is based on a qualitative method, with semistructured interviews with four preschool teachers. The purpose of the study is to investigatethrough interviews how preschool teachers talk about their own participation in children's free play. The study has been formed by two questions; When do preschool teachers participate in children’s free play?and how do preschool teachers describe children’s free play when adults participate? The result of the study has been analysed with support of the pedagogy of free play. The result of the study shows that preschool teachers see free play as important, and that free play creates conditions for children’s learning and development. Despite this, free play is given different amount of time and space in the preschool. The result shows that preschool teachers participate in children’s free play, but the amount of participation differs. The result also showed that preschool teachers participate most in play situations roleplay and building- and construction and that the play is barely affected by their participation. The conclusion is that it is important to have preschool teachers who are present, committed and involved together with the children in their free play.