Since Vietnam, Lao People's Democratic Republic (PDR), Myanmar, and Cambodia joined the Association of Southeast Asian Nations (ASEAN) in the 1990s, concerns have been raised over a Development Divide. The real division is between ASEAN members participating in the integrated East Asian economy and those that do not. The older ASEAN members have become more efficient traders, and Cambodia, Laos, Myanmar, and Vietnam must reform faster if they are to catch up. Cambodia, Lao PDR, and Myanmar are not meeting the challenge, but Vietnam may be leaving the laggards, and the Philippines is lagging the leaders. The challenge is how to avoid a two-tier ASEAN with fast-growing modern economies coexisting besides inward-looking poor countries.