This study aims to develop an instrument that could be used to measure democratic teacher behavior in a valid and reliable manner. The research was carried out in fall semester 2014 to 2015 with a total of 500 high school students recruited from four different schools. Expert opinions were obtained to determine the scale's content validity and face validity. Additionally, exploratory factor analysis and confirmatory factor analysis were performed to assess the construct validity of the scale's measures. Confirmatory factor analysis yielded a construct that is consisted of 17 items and three factors that explained 46,85% of the total variance. These factors were: participation, curriculum and Relations. Findings obtained from confirmatory factor analysis demonstrated that the construct with 17 items and three factors had adequate fit indexes. The reliability of the measures obtained using the three subscales were examined via Cronbach alpha, which produced reliability coefficients that fell within acceptable limits. Based on the research results, it can be stated that the scale is an instrument that produces valid and reliable measures, and that can be used to determine democratic behavior of teachers. Suggestions for future scale development efforts on democratic teacher behavior are outlined.