The purpose of this study is to examine the organization of play space and the effect which this organization has on children's productive and disruptive behavior in an indoor nursery setting. A second purpose was to develop a category system for recording the productive and disruptive behavior of young children in a free play situation. The subjects were 21 4- and 5-year-olds from middle and upper middle class families, attending private nursery school. The effects of two room arrangements were compared: (1) maximum organization, with open paths and one-third to one-half of the available space being an open area, and (2) minimum organization with blocked paths and less than one-third of the available space being an open area. An adapted instrument was developed utilizing categories based on Walters and others and the recording method developed and reported by Caldwell and others. Observations were made over a period of six weeks. Results of the study indicate that during the course of the day children are most often engaged in productive behavior. With maximum organization, children are more verbal than physical, and physical behavior is more productive than disruptive. When the two classroom organizations were compared, significant differences in behavior favoring the maximum organization were found. Sex of the subject was not related to observed behavior. (MS)