In the preschool period, children's friendships considered a crucial developmental task. Hence, it is critical to evaluate children's mental representations of friendships during this period. This study aims to evaluate the validity and reliability of the story completion protocol designed to evaluate preschool children's mental representations of their friendships in school settings for Turkish children. The Preschool Friendship Story Completion Task consists of six stories, one of which is warming. The stories were translated into Turkish by researchers and Turkish-English language experts, and expert opinion was taken for Turkish-English compatibility. Two pilot studies were conducted to evaluate children's participation in the task and following the instructions. Seventy children attending pre-school education institutions participated in the study. Children are asked to complete the unfinished stories presented through a scene and figures. The coders evaluated the video-recorded children's narratives using a detailed rating system. In addition, teachers evaluated the social skills and problem behaviors of children. The results affirmed that the friendship dimensions were conceptually related to each other and the inter-coder reliability was high. Furthermore, our findings indicate that the story completion method on the basis of the narratives of children is a comprehensive and developmentally appropriate way to assess children's friendships.