Abstract This paper aims to explore the theoretical foundations and methodological approaches of public policy evaluation, offering a detailed examination of how different evaluation types assess the effectiveness, efficiency, and impact of public interventions. By examining methods such as formative, summative, result-based, impact, ex-ante, and ex-post evaluations, we seek to understand the distinct roles each plays in shaping public policy outcomes across various domains. Through a comprehensive literature review, the article draws from multiple disciplines, including economics, political science, and public health, to provide a broader perspective on how evaluation frameworks are applied in different contexts. We highlight the challenges that evaluators frequently encounter, such as grappling with the complexity of public issues, the influence of historical decisions, and the political dynamics that often affect policy outcomes. Our literature review reveals that each type of evaluation serves a specific purpose in ensuring accountability, identifying unintended consequences, and measuring both the successes and shortcomings of public policies. This provides essential feedback to policymakers, allowing for continuous refinement and improvement of their strategies. Moreover, the article emphasizes the importance of rigorous protocols and objective assessments to guarantee credible and actionable results. Finally, we conclude by outlining critical areas for future research, such as improving the integration of evaluation methods, addressing evaluation biases, and enhancing the quality and transparency of ex-ante evaluations to further refine public policy development and implementation. Keywords: Public policy, Policy Evaluation, Ex-ante Evaluation, Ex-post Evaluation, Impact Evaluation, Formative Evaluation, Effectiveness Evaluation, Process Evaluation