This research proposal investigates the implications of underage girls' marriage on sustainable development in Egypt. It begins by outlining the prevalence of child marriage in Egypt, particularly in impoverished rural areas, and highlights the role of poverty, ignorance, and societal norms. The proposal poses a research question exploring the impact on sustainable development and outlines objectives to understand the prevalence, influencing factors, and correlation between child marriage and societal growth. The methodology employs a mixed-methods approach, incorporating literature review and primary research, while considering both positivist and interpretivist philosophies. The research will be conducted in Cairo, with limitations acknowledged regarding generalizability due to the scope. The study aims to contribute to understanding the consequences of this practice and propose recommendations to reduce the incidence of underage marriage, emphasizing the need for governmental and non-governmental policies to address the issue.