This study investigates how a teacher study group collectively examined problems in their current English curriculum and redesigned the curriculum into theme-based lessons for various grades. Comprised of seven elementary school teachers and a teacher educator, the teacher study group met bi-weekly for three hours for a total of eight meetings. The transcripts from the group meetings, individual interviews, field-notes, and lesson plans were collected. With the framework of activity theory for data analysis, this study reports on the problems reviewed and identified in the curriculum, and explores how the group worked collaboratively to restructure their English curriculum by developing thematic units incorporating key competencies in the textbooks. The teachers' perceptions towards their participation in curriculum redesign are analyzed and reported.