This study was carried out to develop a valid and reliable measuring tool specific to Turkish culture for determining the authentic leadership levels of school administrators. The research was carried out in 2020-2021 academic years with the participation of teachers who worked in the public primary schools, secondary schools and high schools in Istanbul. Based on the information obtained from the literature screening, the item pool of the draft scale was created. Scope validity analysis was performed using Lawshe technique. After the scope validity analysis, depending on the expert opinions, the item pool was reduced to 30 items. Exploratory factor analysis was carried out with data from 392 teachers. The total variance explained by the scale was determined to be 70.60%. The factor loadings of the items varied from 0.50 to 0.83. Seven Items were removed because they had loadings under multiple factors or had loading below 0.10. The scale was determined to have a 3-factor-structure with 23 items. There were 8 items in the factor of self-awareness, 5 items in the factor of transparency, and 10 items in the factor of decision making and morality. Pearson Product moment Correlation analysis was conducted to determine if there was a meaningful relationship between the exploratory factor analysis and those factors identified. Data from 389 teachers were included in the confirmatory factor analysis In order to check reliability of the scale Cronbach’s Alpha coefficient and Omega was calculated. Also Two Half-Tests (Spearman Brown) and the comparison of the items in the lower and upper 27% groups with the t-test were evalauated. All the analyses were carried out using SPSS 26 and AMOS software. The research results showed that “Authentic Leadership Scale (ALS)” was a valid and reliable measurement tool that has three factors, and could be used especially in leadership studies in educational organizations.