The Thai automotive industry first developed around Bangkok where Japanese car–makers were the first to open plants. During the 1980s, car–makers had to increase their local purchasing to cope with government local content policies. This led to a broader penetration of Japanese parts–makers who also tended to locate their plants close to their affiliated customer. In the 1990s, however, some changes appeared: firstly, the increasing market and the expectation of further growth pushed Japanese car–makers to establish new plants; secondly, the need to cut costs because of increased competition resulted in a new penetration of Japanese parts–makers and subcontractors; thirdly, the excessive concentration around Bangkok pushed the government to implement new policies to develop and industrialize peripheral areas by investing in infrastructures and offering incentives. Additional clusters appeared in several new industrializing areas outside the Bangkok suburb, mainly on the eastern seaboard, with Japanese car and parts–makers opening their new plants in these areas, and with Ford and GM, followed by American parts–makers, also choosing such locations. The article presents these changes in the clustering dynamics in relation to firms’ strategies and public policies, discussing these issues within the framework of the role of the Thai automobile industry in South–East Asia (ASEAN).