Purpose This study was conducted to review the ongoing competency-based education reform in Thailand during the 21st century. In particular, the historical development of Thai competency-based education and the ideological foundation of its competency-based curriculum were explored. Design/Approach/Methods Publicly available policy-related documents addressing competency-based education reform in Thailand were reviewed, and key points that established the ideological foundation of the Thai competency-based curriculum were examined. Findings The development of competency-based education reform in Thailand has changed over time in response to government direction and societal conditions. However, unified ideologies for developing competency-based education are lacking, potentially leading to confusion among the various stakeholders involved. The results of this study indicate that although Thailand's competency-based education system has been developed systematically, it lacks clear communication regarding the driving forces behind the curriculum. Originality/Value This policy review investigated the foundations of Thailand's competency-based education reform to highlight the direction and trends of competency-based education in the country. Competency-based education reforms in Thailand differ from international education reforms—they are founded on a standards-based curriculum and are developed further. This distinction should be considered when assessing the necessity of a competency-based curriculum.