According to Article 25 of Council Regulation (EC) No 58/2003, laying down the statute for executive agencies, an external evaluation on the operation of each agency must be carried out every three years. This Report presents the findings of the external evaluation of the Research Executive Agency (REA) during the period 2018-2021. The evaluation assessed the operation of the Agency and its performance results (effectiveness, efficiency and coherence). It relied on a comprehensive methodology comprising desk research, stakeholder consultation activities and a cost-benefit analysis. During the evaluation period, REA achieved its objectives effectively, and these were aligned with the broader policy goals of the parent DGs. The evaluation showed that communication between the Agency and Commission services was facilitated via well-functioning mechanisms, which were formalised and improved over the evaluation period. This allowed the Commission to focus on its policy-related tasks; however, there was a need to find a better balance between the structured and informal flow of know-how. The Agency was effective and efficient in producing the intended outputs and in achieving its KPIs, which resulted in high levels of stakeholder satisfaction. Overall, there was a consensus that REA’s work during the evaluation period was defined by its stability and efficiency.