Coming out of French colonial rule and central planning, the three transitional economies of Indochina, Vietnam, Cambodia and Lao PDR, embarked on market-oriented reforms in the late 1980s and early 1990s. Vietnam was certainly the most successful, but all three countries quickly achieved macroeconomic stability and rapid growth. However, the Asian financial crisis in 1997/98, as well as the countries’ use of administrative edicts in response to the crisis, highlights the fragile nature of their transition. The paper holds as a premise that effective integration of the three Indochina economies with the “old ASEANS” involves the former developing market institutions that can sustain “quality” growth which will take them out of the transitional economy status. It finds that, although the three economies are open to international trade and investment flows, their domestic market structures are still very much under-developed, with heavy protection of the state sector in terms of tariff structures and bank credits, and inadequate legal and judiciary developments. As a result, foreign investment flows which went principally into the state-owned enterprises in Vietnam and Lao PDR, and into the quota-dependent garment sector in Cambodia, peaked in the mid-1990s and have been declining ever since. Private sector developments have been retarded, and the process of building a commercial/legal infrastructure to support private enterprise has only just begun. Meanwhile, modern production technologies and processes involving component manufacturing in different countries and then assembly in yet a third country (the so-called “component production and assembly within integrated production systems”) means that the cost of doing business includes not just labour cost but also cost of services such as transport, telecommunication, electricity, insurance and banking. The latter are high cost industries dominated chiefly by SOEs in Vietnam and Lao PDR. The bilateral agreements already in place and the WTO agreements (when negotiated) will set deadlines for the three countries to open their service sectors to entry by international firms. Competition has, and will continue, to drive down prices for these services, thereby benefiting the domestic private sector as well as improving competitiveness for foreign direct investments. Implementation of the international trade agreements will also help to streamline cumbersome laws and regulations as well as improve the judiciary in the three countries, again with significant benefits for the domestic private sector. An important challenge is to develop the necessary human resources to complement the countries’ public administration reform. Another challenge is to maintain macroeconomic stability whilst opening the countries’ domestic and external financial sectors. A third challenge for the “New ASEANs” is to counter protectionism of the developed countries with whom they enter trade agreements.