The present study aims to comparatively examine the jurisprudential and legal foundations for determining the age of criminal responsibility of children in the legal systems of Iran and Iraq, clarify the role of jurisprudential opinions in the legislative process, and identify the challenges arising from the conflict between the criterion of Sharia-defined puberty and the requirements of children's rights. The study adopts a descriptive-analytical method with a comparative approach. Data have been collected and analyzed through library-based and documentary research, examining jurisprudential sources, statutory laws, international instruments, legal literature, and judicial cases. The findings indicate that, in Iran, Sharia-defined puberty, based on Imami jurisprudence, constitutes the primary basis for determining the criminal responsibility of children, whereas in Iraq, this determination is based on a combination of Sunni jurisprudential principles and modern legal criteria. Furthermore, differences in the criteria for assessing intellectual maturity, inconsistencies in judicial practice, and challenges related to age determination are among the most significant issues facing both legal systems. Ultimately, greater attention to children's cognitive and psychological development, alongside strengthening protective and rehabilitative approaches, can contribute to achieving criminal justice and safeguarding children's rights.