This article conducts a comparative study of the implementation of two major peace agreements in South Sudan: the 2015 Agreement on the Resolution of the Conflict in South Sudan (ARCSS) and the 2018 Revitalised Agreement (R-ARCSS). It examines the structural, political, and security factors that contributed to the collapse of the ARCSS and analyses the institutional modifications and power-sharing arrangements introduced in the R-ARCSS to address these shortcomings. The study employs a qualitative methodology, drawing on document analysis and secondary sources to assess the comparative efficacy of the two frameworks in achieving transitional security, political inclusivity, and governance reform. The findings highlight persistent challenges in security sector reform and the centralisation of executive power, offering critical insights for future peacebuilding in South Sudan and similar post-conflict states.