This wide-ranging report assesses physical connectivity and cross-border trade across five economic corridors in the Indonesia–Malaysia–Thailand Growth Triangle (IMT-GT). Exploring possibilities for reconfiguring and expanding these vital zones to include further provinces and states, this study analyzes the emerging network of corridors, and examines their uses in major value chains. In addition to mapping the proposed route for a sixth corridor in the IMT-GT, this publication provides details of practical steps and systems that can boost subregional collaboration on the development of all economic corridors in these three countries.