In this study, the relation between the readiness of the 66-72-month-old children in terms of the social skills in pre-service education institutions and their social skills at primary school was investigated. The population of the study consisted of 33 children who attended Marmara University Atatürk Education Faculty Prof. Dr. Ayla Oktay Pre-school Education Application Unit in the 2011-2012 academic year and started primary school in the 2012-2013 academic year. As the study was carried out by means of collecting data from the same population in specific time intervals, it can be described as a longitudinal study. In order to collect data, the Marmara Primary School Readiness Test and the School Social Behavior Scales were used. The readiness of the children for the school in terms of social development during the pre-school education and their social skills were assessed, and the evaluation was conducted again to assess the social skills of the children at the primary school environment. Considering the results of the study, it was identified that preschoolers with ageappropriate level of school readiness and social skills adapt to the school more quickly than their peers and their younger friends when they start primary school. In addition, it was found that the children in the study group performed in accordance with their potentials in their academic studies. The findings were also discussed from the perspective of social adaptation skills of the 66-month-old children who are eligible to start school.