Purposefulness is a key factor in the healthy development of adolescents, but accurate tools for its measurement are limited, particularly in Iran. This study was conducted with the aim of developing a valid and reliable scale for measuring purposefulness in adolescents in Zanjan City. The research method was applied in terms of objective and descriptive-correlational in terms of data collection approach, with an emphasis on Confirmatory Factor Analysis (CFA). The psychometric properties of the instrument were evaluated, including its reliability and validity. The descriptive-correlational study was conducted on 390 middle and high school students in Zanjan (mean age: 16.08 years), using a convenience sampling method. The results indicated that the scale possesses acceptable reliability: the Cronbach's alpha coefficient for the entire scale was 0.75, ranging from 0.70 to 0.77 for the subscales, and the test-retest correlation coefficient after one week was 0.88. The results of the Confirmatory Factor Analysis (CFA) demonstrated that purposefulness, as a higher-order construct, can be examined through four factors, including Goal Attainment, Self Enhancement, Career Orientation, and Relationship Orientation. This structure was confirmed by the CFA, and it was also determined that purposefulness is closely related to psychological well-being and meaning in life. The Purpose In Life Scale for Adolescents is a valid and reliable instrument that can help identify and strengthen the life trajectory during the sensitive period of adolescence. This instrument is applicable not only in research related to purposefulness but also in designing effective interventions to promote adolescents' psychological well-being. Given its favorable psychometric properties, this scale provides a suitable platform for future research in developmental psychology and educational interventions.