The purpose of this study is to compare the assessment results of social skills of students with mental retardation by their teachers and mothers through relational model by using descriptive statistics. The research group in this study consisted of mothers and teachers of 562 children with mental retardation aged between 6 and 12 who enrolled in special education schools and special classes. For 6-12 age group, Teacher Form of Social Skills Rating System (SSRS-TF) and Parent Form of Social Skills Rating System (SSRS-PF) were used to collect data. Initially, this study investigated whether there was a relation between the mother and teacher assessment results of social skills of students with mental retardation. Then it examined whether the social skills of students with mental retardation differ according to the various variables such as gender, age, level of retardation, and additional disability. According to the results of analysis, a high correlation was found between the total scores of social skills scale obtained after mother and teacher assessments. Additionally, a high correlation was found between externalizing behavior subscale score and hyperactivity subscale score and the assertiveness subscale score of teachers and parents forms. Moreover, a high correlation was observed between the total scores of problem behavior subscales of teachers and parents forms. There is a moderate relationship between cooperation skills subscales score, self-control skills subscales score and internalizing problem behaviors subscales score. In addition, the social skills of the girls are more than those of the boys, and their problem behaviors are lower than those of the males. The social skills of the students with mental retardation who are in 6-9 age group are significantly lower than those of the students who are in 10-12 age group, and problem behaviors do not differ according to age of the students.