The effects of changes in spatial density on preschool children's behavior were examined in a quasi-experimental study involving repeated measures taken on two experimental groups and one control group. Subjects were all 59 children registered in three rooms of a non-profit public day care center in Edmonton, Alberta, Canada. Both quantitative and qualitative data were gathered. Room scan and child scan methodologies were used to measure children's behavior. By using a model of the day care room, interviews were conducted among selected, articulate children exposed to the spatial change. Staff exposed to the change were also interviewed. In the experimental rooms, density was altered from low to high and back to low for the initial 2, medial 3, and the final 2 weeks of the study respectively. Barriers were used to reduce the amount of uncovered space by approximately 40%. Density in the control room was low for the entire 7 weeks. A summary of the findings from the room and child scans and the complete discussion of the child and staff interviews are provided in this report. Related materials, including child scan recording sheets and coding categories, diagrams of rooms in regular and compacted conditions, as well as interview protocols and selected responses, are appended. (Author/RH)