Learning ought to be supported by both in class activities and outdoor activities contributing to structuring knowledge. Outdoor activities allow children to actively participate and to learn by doing. Learning requires a lot of work and activities. These activities, which provide primary experiences, help children to change theoretical knowledge into practice, record it in the long-term memory, and create solutions to problems they encounter in daily life, based on what they have learned. Children, especially preschoolers, can record things into their long-term memory in learning environments which stimulate all the senses. Based on these ideas, this study was directed towards revealing effects of outdoor activities on cognitive, motor, linguistic and social-emotional development of preschool children. Thirty-five preschool children living in disadvantageous districts in Izmir, Turkey, and not being able to get education, were offered ten-week preschool education involving outdoor activities. This research was designed according to one group pre-test and post-test model. The results show that outdoor activities improved cognitive, linguistic, social-emotional and motor skills of preschool children.