The problem raised in the article is to analyze the internal models created by children in the perception of the social world, in particular, friendships. The aim of this research is to study the conceptualization of the phenomenon of friendship by primary school children with intellectual disability. Materials and Methods. The study involved children of primary school aged 9-11 years. The experimental groups were diagnosed with «mixed specific developmental disorders» and «mild mental retardation». The authors employed the following research methods: a standardized interview, sociometry, “relationships with close people” questionnaire, “perceptions of friendship” questionnaire, incomplete sentences; projective methods (drawing and essay on the topic “My friend”). Results. On the basis of factor analysis, the authors have identified three main factors which describe the main concepts of friendship: the nature of relationships, the motivation for choosing a friend, and the image of a friend. The results of a comparative analysis indicate that the internal concepts of the phenomenon of friendship of children with intellectual disability differ from normatively developing peers by violating abstraction and are associated with the reflection of concrete facts from personal life experience. Conclusions. All the data indicate that the domestic concept of the phenomenon of friendship in children with intellectual disability are poorly abstracted, tied to specific events and phenomena. The features revealed in the course of the present experimental study are evidence of the immature nature of the mental model in children with intellectual disability, which causes difficulties in the adequate conceptualization of the phenomenon of friendship.