This study discusses the problem of child marriage in Libya، highlighting its negative effects on girls' mental health، including psychological disorders and repercussions on their social and psychological well-being. It also indicates that the prevalence of this phenomenon is linked to several social and legal factors. The study addresses a range of theoretical and procedural concepts، including the theoretical definition of child marriage and its legal definition in Libyan law. The study clarifies the age of majority according to Libyan law، which is set between 18 and 20 years. It also identifies several factors that influence early marriage، including customs and traditions، as well as legislation that sets the legal age of marriage. This study aimed to identify the psychological and social effects of child marriage، focusing on the Libyan context، particularly in the cities of Benghazi and Tobruk. It explored the prevalence of this phenomenon، its impact on mental health، and its contributing factors. Four cases were examined from Benghazi and one from Tobruk، employing a case study methodology. The study revealed that child marriage causes numerous psychological problems، including depression، anxiety، panic attacks، and psychological trauma. It also indicated that girls suffer from psychological stress due to early pregnancy and a lack of psychological and social readiness for responsibility. Their personalities are negatively affected، and they experience low self-esteem and social isolation. The study identified several contributing factors to the spread of this phenomenon، including religious and social factors، customs and traditions، weak legal procedures، the lack of enforcement of marriage age laws، economic pressures that push families to marry off their daughters early to reduce expenses، and a lack of sufficient awareness about the dangers and psychological harm of early marriage. One of the most important findings of this study is that child marriage leaves profound psychological effects، ranging from mental disorders and anxiety to depression، resulting from the major life changes and the girls' lack of psychological and social maturity. Keywords: marriage، minors، psychological effects، isolation، children، Libyan law.