This article aims to examine the development of business groups in Thailand. It considers business groups, not just as a response to market failure or institutional voids in emerging markets, but as vehicles for economic catch-up with more industrialized nations. This article briefly describes the development of business, with an emphasis on family-run groups, and their survival despite changes in economic and political environments until the 2000s. It then sketches the structure of ownership and management of family business groups. It also examines the business diversification and internationalization strategies of major business groups before and after the 1997 Asian financial crisis. It also looks at the impacts of the crisis, and at corporate governance reform, focusing on the banking sector and listed companies. Finally, this article concludes by looking at the competitive capabilities of leading Thai business groups, and considers their future challenges.