Purpose: What does it take to successfully implement new educational innovation in schools, and what roles does lesson study play there? In order to answer this question, this study investigated the implementation of Sesame Street's Dream-Save-Do (DSD) curriculum that was designed to help children in a Japanese elementary school learn to pursue their own dreams. Design/methodology/approach: The authors first reviewed available documents on the DSD curriculum in the district, and then conducted DSD class observations. The authors also interviewed the students, teachers, the principal, the lead teacher at the school, the school district staff in charge of the operation as well as the Sesame Japan staff in order to collect the data for the study. Findings: The study found that students were highly engaged in open-ended discussions about their future dreams and how to achieve them in observed DSD classes. The implementation of the new curriculum benefited from utilizing lesson study as the main arena for curricular innovation. A further analysis of the data suggests that the success of the curricular innovation owed much to an inside-out implementation process that situated the iterative lesson study cycle of the teachers as the key driver of change while external actors supported the lesson study process in an inside-out fashion. Research limitations/implications: The study implies that guiding an educational innovation to success requires not only institutionalized lesson study, but also cross-institutional collaborative dialogues to support the lesson study process with mutually established trust among key players of the innovation. Further studies are needed to investigate how this model sustains as principals and how this model works (or do not work) in other pilot schools and beyond. Practical implications This study implies that what matters most is that the school embodies a vision shared among teachers, school leaders and external curriculum developers, all working together across institutions in a spirit of collaboration. This type of inside-out implementation would be a path to ensure and sustain the success for those who plan any new educational innovation. Social implications: What matters most was found to be that the school embodies a vision shared among educators, school leaders and external curriculum developers working together across institutions in a spirit of collaboration. Originality/value: Guiding an educational innovation to success requires not only new ideas and effective curriculum plans but also a social structure that allows teachers to engage in effective implementations of the desired curriculum. Lesson study is often considered to be a within-school or school-to-school collaborative process. It is rarely connected to outside agents that bring in new ideas for educational innovation. This study found how inside- and outside-school actors can work together to actualize educational innovation, and what roles lesson study play there.