The purpose of this study is to measure the effect of recreational activity-based program on the social skills of mentally retarded students. The research sample is composed of a total of 50 educable mentally retarded students - 31 males and 19 females - aged between 9 and 12 who regularly attend Private Gal Bahcesi Education and Rehabilitation Center situated in Tuzla district of Istanbul province. Preliminary test, final test and uncontrolled group experimental model were used in the research. The program containing different activities in 2017 was applied for 13 weeks. Personal information form and Social Skills Evaluation Scale were used as data collection tool. Data were analyzed with SPSS 21 package program. Frequency and percentage distributions, Cronbach's Alpha, Shapiro Wilk-W and Wilcoxon test were applied. As a result of the research, it has been determined that recreation-based program has a positive effect on social skills of mentally retarded students. Significant differences at the level of 0.05 have been found between preliminary and final test. Considering and applying such activities for the development of retarded individuals as an alternative education can be useful.