This study aims to compare the Shura, Representatives, National, and Union Councils in the Gulf Cooperation Council (GCC) countries, considering them as parliamentary representative bodies. In light of their assigned roles, we attempt to present a comparative overview of the powers of these councils and their relationship to the constitution, which regulates the public authorities of the state. Accordingly, the roles and public powers granted to parliamentary councils are defined. Through an analysis of the internal working systems of these councils, we explore their actual performance to reveal their true roles in shaping and guiding the public policies of these countries, based on the legislative and oversight functions of parliaments. To achieve this, we will adopt a case study approach as our methodological method and content analysis as our research tools. Our theoretical analysis will be based on the criteria of the Inter-Parliamentary Union's Guide to Good Parliamentary Practice, as follows: - Comprehensiveness of structure and performance methods. - Effectiveness of communication with the public. - Experimenting with new methods of communicating with the public, including civil society, and enabling its participation in legislative processes. - Restoring public confidence in the integrity of parliamentarians. - Streamlining legislative procedures. - Enhancing the effectiveness of oversight of the executive branch. - Efforts in the areas of cooperation between states and conflict resolution. Given the constitutional powers that grant the Gulf Cooperation Council's representative councils their parliamentary function, we will examine the role of these councils in shaping and guiding public policies. This examination stems from their active participation in development work through their legislative performance, their oversight of the executive branch, their involvement in preparing and reviewing development plans, and their approval of financial budgets. This includes the subsequent monitoring and oversight of the implementation of these plans and budgets................ Keywords:........... Parliamentary Councils, Legislative and Oversight Function, Public Policy .