The aim of this study is to develop a scale to determine foreign language teachers’ authentic material use. To develop this scale, inventories and literature concerning the subject have been reviewed. 20 foreign languages teachers were asked to write paragraphs on authentic materials. An item pool of 44 items was created, corrected and reduced taking expert opinion. It was seen that the scale could consist of four sub scales, which are increasing student motivation, enriching the course content, increasing the quality of teaching, introducing real life/culture. Considering expert opinion a five-point Likert type pilot form of 25- items was created and conducted on 146 English language teachers working in public and private schools. The result of the chi-square difference test for nested models, the model data fit of the four-factor model was found to be significantly higher compared to the one-factor model (Δχ2(6)= 88.42, p ˂ .001). The confirmatory factor analysis shows that the designed four-factor model complies well with the data and explains the data better than the one factor model and supports the researchers' observations. The analysis shows that the four factors designed FLTAMUS has construct validity. Cronbach alpha internal consistency coefficients of the subscales vary between .65 and .91. and are quite reliable and highly reliable. The applied validity and reliability analyses show that the scale has four structures as designed and is a valid and reliable measurement tool that can measure foreign language teachers’ use of authentic materials.