The research aimed to identify the clinical implications of the Family Understanding Test (FAT) in detecting the dynamic factors of kleptomania among primary school students, identifying the underlying subconscious factors that push children to steal, and revealing their psychological structure. The researcher used the clinical approach (case study) for the case of a ten-year-old girl in the fifth grade of primary school who suffers from kleptomania. The researcher used the Abdel Moati case history study form (1998), observation, the clinical interview form for kleptomania prepared by the researcher, and the Family Understanding Test (FAT) prepared by (Sotile et al., 1999), in addition to research reports, of which the most important is the social report by the school social worker. Besides, community sources, of which the most important is the family. The condition was diagnosed in light of the Diagnostic and Statistical Manual of Mental Disorders. The research results revealed the presence of personal dynamics and subconscious factors characteristic of a kleptomania patient, the emergence of a negative self-image, low self-esteem, and loss of self-confidence, in addition to the effectiveness of the Family Understanding Test (FAT) in revealing the underlying factors that led the case to steal, as the case lives in a family environment full of With family and marital conflicts and the parents’ inability to satisfy her psychological needs, which led to the emergence of psychological and behavioral problems in the case. The research also presented some recommendations and proposed research.