The Securities and Exchange Commission (SEC) introduced the Investment Governance Code for Institutional Investors (Thai Code) in 2017 as an integral part of its corporate governance framework. The previous success of the Thai Corporate Governance Code (CG Code) in reforming the Thai corporate governance system was largely owing to the active collaboration of all stakeholders following the 1997 Asian Financial Crisis. The SEC aims to continue this success with the Thai Code, but, as this chapter explains, this is unlikely. The chapter introduces the CG Code and its success in Thailand, as background for understanding the Thai Code, to demonstrate that institutional investors in Thailand have had a limited impact as stewards. The Thai capital market is dominated by local private companies – especially family businesses – which often assume the role of de facto ‘stewards’ in most Thai companies. The chapter analyzes how institutional investors, especially asset management companies, have implemented the Thai Code, then concludes by highlighting how in-depth empirical and case-study analysis is required to understand the complexity of how the Thai Code works in practice.