This study was to explain the concept of assertiveness and quantify the reliability and validity of the Turkish version of the "Four Dimensions of Assertiveness" scale developed by Lorr & More. One hundred and twenty-eight students from Sinop University, Turkey completed the Four Dimensions of Assertiveness scale. Cronbach's alpha was calculated to quantify internal consistency of the scale. Construct validity was evaluated using factor analysis. Items with a factor loading value less than 0.25 were removed from the scale. Internal validity was evaluated by comparing the top 27% of scores to the bottom 27% of scores using an independent t-test. Cronbach's alpha was 0.637, indicating moderate internal consistency. Of the 33 items included in the scale, 11 had a factor loading value less than 0.25 and were removed. The remaining 22 items had factor loading values between 0.261 and 0.842, and the factors were gathered in four groups: directiveness, social assertiveness, defence of rights and independence. These results indicate that the Turkish version of the Four Dimensions of Assertiveness scale is a reliable and valid scale for measuring assertiveness in a Turkish population. © Sila Science.