The current study was conducted to investigate the contribution of the forest school approach to the development of preschool children. In this connection, the study group is comprised of 7 pre-schoolers aged at 48-60 months. The sample of the current study was determined by using the convenience sampling method, one of the purposive sampling methods. The current study is a case study, covering an eight-week period. A total of five data collection tools were used in the study: "General Information Form", "Pre-Application Questions", "Activity Evaluation Form (Individual)", "Activity Evaluation Form (General)", "Development Observation Form". The collected data were transcribed; codes and themes were established and finally content analysis was conducted on them. As a result of the analysis, it was concluded that the forest school applications positively affected the children's cognitive development, language development, social and emotional development, motor development and self-care skills in some situations and supported the development of the children in general. In light of these findings, integration of forest school into pre-school education is thought to be of great importance.