Tehran University of Medical Sciences Iranian Journal of Psychiatry 1735-4587 7 3 2012 09 15 126 34 Shahrum Vahedi Department of Psychology, University of Tabriz, Tabriz, Iran. Farahman Farrokhi Fathemeh Farajian 2015 10 14 Objective: This study examines development of social competence, and behavior problems in kindergarten children during a specific period of childhood. Method: A sample of 499 kindergarten children (244 girls and 255 boys) with the age range of 2 years up to 5 years and 6 months was selected using the random stratified sampling method. To collect data, California Preschool Social Competence Scale and Social Skills Rating System were completed by kindergarten teachers. Results: The trend analysis shows that both the linear and quadratic trends for verbal facility were statistically significant. Similarly, both the linear and cubic trends were significant for considerateness, and the linear trend tendency was significant for subscales of extraversion, response to unfamiliar and task orientation. Pearson's correlation coefficient yielded a low-to-moderate and negative correlation patterns between social component and problem behaviors.  Conclusion: The study findings indicate a significant linear trend between the progression in social competence and increasing age, consequently leading to a decrease in social problems for children whose age was from 2 years up to 5 years and 6 months. https://ijps.tums.ac.ir/index.php/ijps/article/view/234 https://ijps.tums.ac.ir/index.php/ijps/article/download/234/230