This paper presents the experience of going to scale of Escuela Nueva, an educational innovation that started in Colombia and has influenced educational policy in several countries around the world during the last 30 years. The paper is based on the experience of the leaders of the innovation and its expansion over time. As an insider´s perpective, it relies on the knowledge of senior staff of Fundación Escuela Nueva and on the published evidence and experience accumulated during the decades following the creation of the innovation. The paper describes the context where Escuela Nueva was created and the practices of participating students, teachers, schools administrators and parents when undergoing learning and teaching. It presents the conceptual underpinnings of the innovation, and discusses existing evidence of impact of Escuela Nueva on students, teachers and parents. It then examines the experience of bringing Escuela Nueva to scale, using a three-stage framework: learning to be effective, learning to be efficient and learning to expand. The paper then discusses key factors for success, and the challenges of scale, impact and sustainability, and advances the argument that good design, adequate implementation and sustained support are essential to take an innovation to scale. To conclude, the following four key lessons of Escuela Nueva to the educational change field are discussed : (1) Teachers and students need to be the key actors of the change; (2) the proposed improvements have to be easily replicable within existing conditions; (3) the attitudinal change of teachers is positively affected as a result of demonstrating that the model was feasible, a good fit for its beneficiaries and that they could do it; and (4) a systemic approach is necessary to impact simultaneously on the critical factors of success.