The purpose of this study was to develop a scale for assessing teachers' self-determination instruction and to test the validity and reliability of this tool. The subjects included 315 teachers recruited from elementary and junior high schools nationwide in Taiwan. The Teaching Self-Determination Scale (TSDS) developed in this study aimed at assessing the extent to which educators teach students knowledge and skills related to self-determination. The 24-item TSDS is comprised of four subscales including Self-Realization, Psychological Empowerment, Self-Regulation, and Autonomy. Data collected were analyzed using descriptive statistics, correlation analyses, t tests, and factor analyses. Findings showed that the TSDS has satisfactory psychometric properties. The internal consistency reliability coefficients (Cronbach's a) ranged from 0.76 to 0.93, while the test-retest coefficients ranged from 0.71 to 0.87. Findings of the exploratory factor analysis showed that the four TSDS subscale factors can be reasonably extracted, which can explain 59.7% of the total item variance. The confirmatory factor analysis results further indicated a good fit between the measurement model and the sample data (GFI = 0.96, AGFI = 0.91, RMSEA = 0.08, NFI = 0.97, RFI = 0.93, IFI = 0.98, TLI = 0.95, CFI = 0.98). Suggestions are provided for future research.