Öz Problem Statement: The educational technology standards for teachers setby the International Society for Technology in Education (the ISTEStandards-T) represent an important framework for using technologyeffectively in teaching and learning processes. These standards are widelyused by universities, educational institutions, and schools. Thecontemporary ISTE standards for teachers proposed in 2008 have fivedimensions. The standards created a vision for the educational technologyfield, so it is important that how prospective teachers or in-service teachersmeet these standards is measured with valid and reliable instruments.Purpose of the Study: The purpose of this study was to develop and validatethe education technology standards self-efficacy (ETSSE) scale, which isbased on the ISTE Standards-T.Method: Confirmatory factor analyses (CFA) were conducted in order todetermine the factor structure of the scale. The scale items wereconstructed based on the ISTE Standards-T and performance indicators.To define the content validity values of the scale items, the researchersasked the opinions of 12 specialists. The data was collected fromprospective teachers (CFA1 group, n=473) and teachers (CFA2 group,n=394). Owing to the theoretical structure of the standards being defined by ISTE, both first order and second order confirmatory factor analyses were applied to the datasets of the two groups separately and without exploratory factor analysis.Findings: The ETSSE scale was validated in five dimensions as ISTE Standards-T 2008 identified. According to the results of the first order and second order confirmatory factor analyses (CFAs) of the two different groups, the scale is considered reliable (CFA1 1st order [χ2 (734, n= 473)= 1857.23, p< .001, RMSEA=.057, SRMR=.053, NFI= .95, NNFI=.97, CFI=.97, IFI=.97]; CFA2 1st order [χ2 (727, n= 394)= 1886.31, p< .001, RMSEA=.064, SRMR=.056, NFI = .95, NNFI=.97, CFI=.97, IFI=.97]). Concurrent validity results showed a positive and significant correlation between the two scales .83 (p<.01). Cronbach’s Alpha was at .95 and McDonald’s Omega was .96. The item analyses showed that each item correlated with the overall score from the scale both for prospective teachers and teachers (Corrected Item-Total Correlation >.30). Independent group t-tests for the 27% upper and 27% lower groups in the five sub-factors showed significant difference (p<.01).Conclusion and Recommendations: The research results have demonstrated that the developed ETSSE scale consisting of 40 items and five subscales is valid and reliable for both teachers and prospective teachers.Keywords: Education technology standards, ISTE standards, scale development, confirmatory factor analysis