Background: The construct of self-determination has received considerable attention in the international field of intellectual disabilities (ID). Recently, there has been a rapid development of this construct in Chinese societies including Hong Kong. However, there is no locally validated instrument to measure self-determination in people with ID. This article explains the validation process of the AIR Self-Determination Scale-Chinese version (AIR SDS-C) adapted from the 24-item AIR Self-Determination Scale, developed by Wolman and his colleagues, which is used in school setting. Methods: People with mild/moderate ID aged 15 years or above were recruited from special schools and social services units in different regions of Hong Kong. Factor analysis and reliability tests were conducted. Results: Data for a total of 356 participants were used for the analysis. A confirmatory factor analysis was performed to test the factorial construct, and Mplus 7.0 was used for the analysis. The factor structure proposed in the original English version was supported by the data, and all factor loadings were between 0.42 and 0.76. The whole scale achieved good reliability (Cronbach's a = 0.88 and ? = 0.90). Conclusions: The AIR SDS-C appears to be a valid and reliable scale. This study examined adult groups as well as student groups. The application of the scale can thus be extended to a wider population. The implications for theory building and practice are discussed.