The Asian Development Bank and the Association of Southeast Asian Nations and the People's Republic of China, Japan, and the Republic of Korea (ASEAN+3) are looking to explore options to promote green local currency-denominated bonds to meet the region's infrastructure development needs. Green bonds---supported within the ASEAN+3 framework---would help meet the long-term financing of the region especially in its transition to a low-carbon region. This publication highlights an assessment study of green bond markets in ASEAN+3, identifies the barriers to green bond market development, and proposes recommendations to scale up green bond markets for infrastructure development in ASEAN+3.