The aim of the present investigation was to develop a comprehensive tool to measure positive sexuality among adolescents. We first conducted an extensive literature review to develop the Positive Sexuality in Adolescence Scale (PSAS). We also conducted focus group interviews with adolescents (N = 14) to explore their understanding of positive sexuality and to discuss the proposed scale items. In two survey studies (Ntotal = 890), we examined the psychometric properties of the Positive Sexuality in Adolescence Scale (PSAS). In Study 1 (N = 211; Mage = 15.5, 55.5% girls), an exploratory factor analysis yielded five factors (e.g., positive approach to sexual relationships) which comprised 22 items. Convergent validity was also established in Study 1. In Study 2 (N = 679; Mage = 15.32, 49% girls), a confirmatory factor analysis confirmed the factor structure. Results of Study 2 also supported the internal consistency and a partial strong measurement invariance for gender. The PSAS may be a useful tool for assessing the multifaceted nature of positive sexuality among adolescents, regardless of a person’s gender. Maes, C., Trekels, J., Impett, E., & Vandenbosch, L. (2022). The Development of the Positive Sexuality in Adolescence Scale (PSAS). The Journal of Sex Research, 1-17. https://doi.org/10.1080/00224499.2021.2011826