This exploratory study investigates teachers’ attitude toward Lesson Study (LS), a professional development approach which is relatively unknown in the Netherlands. The paper reports a qualitative study based on the Reasoned Action Approach, which explains how teachers’ beliefs influence their intention to engage in Lesson Study in the context of an interschool Professional Learning Community (PLC). 26 teachers of two PLCs were interviewed before their participation in LS and after the execution of two LS cycles during one school year. The interviews were content-analyzed. The findings show that the teachers felt relatively positive about the LS project before the start, and that after one year this positive attitude had slightly increased....