Time attitudes (TA) are evaluative feelings toward the past, present and future. Given the role of TA in psychological and behavioral outcomes, the aim of this study was to analyze the adequacy of the Adolescent Time Inventory-Time Attitudes (ATI-TA) scale among adolescents and young adults in Italy. The scale was administered to 638 students in order to test its psychometric properties and validity. The analyses confirmed the adequacy of the six-factor model and the reliability of the subscales. Additionally, the measurement invariance of the scale across genders and age groups (between adolescents up to the age of 18, and young adults above 18) was demonstrated. Specifically, gender invariance reached the level of equivalence of error variances/covariances, and the same level was partially reached for invariance across age groups. Evidence of the validity of the scale was also provided by obtaining significant correlations between the subscales, and self-esteem and strategic learning. Taken together, these results support the suitability of the ATI-TA to be used for research and clinical purposes.