Two groups of 1 and 3 year-old nursery school children were observed using ethological method. Children's interactions over objects possessed by one of them were recorded. The data was analysed to find out whether these interactions were organized under rank order like Dominance Hierarchy, or under the principle of respect for occupancy, which make children respect any other possessions. Findings were; 1) Children had established the principle of respect for occupancy as early as 3 years of age, 2) the data couldn't be explained by the concept of rank order or Dominance. It was emphasized that the establishment of the principle didn't mean that children had given up using other's possessions, but that they came to be able to share the object in order to play together.