Middle childhood is an important period for reducing social and behavioural difficulties, though existing social skills training programs in Lithuania are not effective to help solving these problems. The aim of this study was to create and evaluate the short-term and long-term effects of a social skills training program based on an integrated theoretical model for second grade schoolchildren. The purpose of the program was to teach children non-verbal language, empathy, conflict resolution, and problem-solving skills. Social skills were measured using the Primary School Social Competence Scale (Magelinskaite, 2010) and Strengths and Difficulties Questionnaire (Gintiliene, Girdzijauskiene, Cerniauskaite, Lesinskiene, Povilaitis, 2004). The sample for this study was taken from one of the Catholic schools in Lithuania. From 42 second grade students, 24 were chosen and divided into two equal groups (experimental and control). The first screening was carried out before the social skills training, the second - one week after the training, the third - 3 months after the training. The results showed that self-control and conflict resolution skills significantly improved in the experimental group after the program, while interpersonal skills, ability to solve casual problems did not change significantly. Also, self-control skills improved significantly in three months after social skills training than before participating. In the control group, these skills did not change significantly directly after the program and there were no differences after three months from participation. This study has shown that the social skills training program can contribute significantly to the development of the second graders' conflict resolution skills and can have long-term effect on self-regulation skills. However, future studies should evaluate the social skills training program using a larger sample size and more focused statistical tests. (C) 2017 Published by Future Academy www.FutureAcademy.org.UK