The purpose of this study was to adapt Reflective Thinking Scale to Turkish and investigate its validity and reliability over a Turkish university students' sample. Reflective Thinking Scale (RTS) is a 5 point Likert scale (ranging from 1 corresponding Agree Completely, 3 to Neutral, and 5 to Not Agree Completely), purposed to measure reflective thinking in habitual actions, understanding, reflecting and critical reflecting subscale levels. With the help of education area and language experts, the scale adaptation thoroughly completed and the correlation between the original scale and its Turkish form indicated satisfactory language equality (r=0.80). During the 2011-2012 school years, 1413 undergraduate students, from varying departments of Faculty of Education, Canakkale Onsekiz Mart and Gaziosmanpasa University, were participated in this study. In order to maximize student participation, convenient sampling method was followed. After the item analysis, internal consistency of the scale and subscale items were checked through Cronbach Alpha internal consistency coefficient and Spearman Brown Split-Half correlation coefficient and both indicated good internal consistency on the scale and the subscale levels. The scale also demonstrated sufficient test-retest reliability over the application of the scale in two weeks and two months intervals. The construct validity is established through a confirmatory and an exploratory factor analyses and the four factor structure, suggested in the original study, was confirmed by both analyses. The concurrent validity was also confirmed through the scale's satisfactory Pearson correlation coefficient with Critical Thinking Scale.