This study aims to develop a multidimensional 21st century skills scale for adolescent and early adulthood students in the 15-25 age group. The research was conducted with 660 high school, associate degree and undergraduate students. From the item pool created during the first stage of the study, 146 items were selected in line with expert opinions. Within the scope of the validity studies, exploratory factor analysis was carried out. As a result of the analysis, a 41-item scale with five sub factors were developed. In the second stage of the study, Lisrel 8.80 program was used with confirmatory factor analysis, and the five sub-factor structure was confirmed. In the third stage of the study, the test--retest method was applied, and the mean scale scores and standard deviation values of the scale in the first and second applications were found to be 3.89, 18.21 and 3.58 and 22.19, respectively.