This study is therefore aimed at contributing to the discussion of corporate governance by delving into the empirical evidence on how firms with different corporate governance classes perform in Thailand. The motivation of this study stems not only from the fact that, in the past, most firms in Asia overlooked the concept of corporate governance, but also from the fact that corporate governance has become an increasingly important concern since the 1997 Asian financial crisis. A failure to fully grasp he cost and benefit of corporate governance may result in either the firm only paying lip service to corporate governance for the sake of better public relations, or the firm ending up excessively championing the cause whence their resources could better be utilized elsewhere. It is for this very reason that this study chooses to focus on improving the understanding of the effects of corporate governance on equity returns.