The purpose of this study is to examine whether the peer relationships and social position levels of 5-6 year old children have a predictor effect on their school adaptation level or not. The sample group of the study is consisted of 175 (91 female, 84 male) children, who continue to receive preschool education in Serinhisar and Tavas districts of the city center of Denizli during the school year of 2010-2011, and 12 kindergarten teachers. In the study, “Personal Information Form, Ladd and Profilet Child Behavior Scale, Peer Victimization Scale, Teacher Rating Scale of School Adjustment for 5-6 Year Olds, Picture Sociometry Scale” were used as data collection tools. Multiple regression analysis was used for the analysis of the data. The study results concluded that prosocial behavior variable of 5-6 year old children is the variable that predicts school adaptation at highest level for four measurements throughout the school year. In general, other variables that predict the school adaptation are anxious- fearful, aggression, asocial behavior, hyperactivity and social position. The variables that do not predict the school adaptation in a statistically significant way were the variables of exclusion and peer victimization. As the prosocial behavior and social position levels increase, the level of school adaptation increases as well. It is observed that as the levels of the variables of anxious-fearful, asocial behavior, hyperactivity and aggression increase, the level of school adaptation decreases. Leaving the mother’s bosom and starting the kindergarten is the biggest change in children’s lives. The child not only becomes the member of a peer group, but also gets the opportunity of being acquainted with the teacher and the concept of school by starting the kindergarten. Starting the kindergarten represents the process of adjustment for both children and parents. Children who receive preschool education primarily get separated from the family environment and experience the excitement of being involved in a different environment. Thus, both the school and the family should have numerous duties for the child to overcome this process in a compatible way. Relational survey method was used in the study. Relational survey method includes the research models that aim to determine the existence and/or extent of the covariance between two and more variables (Karasar, 2009: 81). The data collection process was performed four times in a year. Preschool teachers filled the “Child Behavior Scale, Peer Victimization Scale, and Teacher Rating Assessment Scale of School Adjustment” for each child once during each application period. These scales were completed by the teachers four times throughout the study. The researcher applied the “Picture Sociometry Scale” individually to each child for once during each data collection process and totally four times throughout the study. During the application, children were shown the pictures of their friends, asked 4 questions and the scores of each child were recorded in line with their answers. The average duration of application was 15 minutes for each child. In order to determine whether the peer relationships and social position level have a predictor effect on the level of school adjustment or not, multiple regression analysis was performed during analysis of data. The SPSS 16.00 software was used to test analyses in the computer environment. According to the first measurement results of the study; the variables of prosocial behavior, asocial behavior, fearful- anxious, aggressiveness and hyperactivity significantly predict the level of school adjustment. The variable that predicts the school adjustment at the highest level is the prosocial behavior. It is respectively followed by the variables of asocial behavior, fearful- anxious, aggressiveness and hyperactivity. A positive relationship was determined between the levels of prosocial behavior and school adjustment. As the level of prosocial behavior increases, the level of school adjustment increases as well. As the levels of aggressiveness, fearful- anxious, asocial behavior and hyperactivity increase, the level of school adjustment decreases. However, each of variables of peer victimization and social position do not predict the level of school adjustment in a statistically significant way. Reason behind this result is that children do not interact with each other since they do not get acquainted in the beginning of the school year, and this result might be an indicator of the personal effort for school adjustment. In the second measurement, the variables of prosocial behavior and social position individually predict the school adjustment significantly. Just like in the first measurement, the variable that predicts the school adjustment at the highest level is the prosocial behavior. Social position is the second variable that predicts the school adjustment. There is a positive relation between the levels of prosocial behavior and social position and the level of school adjustment. As the levels of prosocial behavior and social position increase, the level of school adjustment increases as well. Each of variables “aggressiveness, exclusion, fearful- anxious, asocial behavior, hyperactivity and peer victimization” does not predict the level of school adjustment in a statistically significant way. Social position is the second variable that predicts the school adjustment. According to the results of the third measurement, the prosocial behavior is the variable that predicts the school adjustment at the highest level. It is respectively followed by the variables of asocial behavior, fearful- anxious and hyperactivity. It is observed that the level of school adjustment increases as the level of prosocial behavior increases; and the level of school adjustment decreases as the levels of fearful- anxious and hy