The psychometric properties of the Revised Child Anxiety and Depression Scale (RCADS-47) are established cross-culturally but lacking for the Greek population. The present study examined RCADS internal consistency and validity (structural and concurrent) in Greek adolescents, and tested measurement invariance across sex and age groups. We recruited 619 secondary school students (n = 321 females), aged 12-18 years (n = 318, 12-14-year-olds). Besides RCADS, all students completed Strengths and Difficulties Questionnaire (SDQ), a subsample (n = 300) completed Screen for Child Anxiety-Related Emotional Disorders (SCARED), whereas a non-overlapping subsample (n = 219) completed Depression Self-Rating Scale (DSRS). Structural validity was examined with Confirmatory Factor Analysis and measurement invariance was assessed with Multiple Indicators Multiple Causes (MIMIC) modeling. Convergent and divergent validity were examined using Spearman correlations between RCADS subscales and DSRS, SCARED, and SDQ validators. The six-factor model fitted the data best, validating the originally proposed RCADS structure. Three items displayed differential item functioning for sex, another three for age group, and one item for both, albeit with trivial effect sizes (d < 0.2). Cronbach's alpha was .94. Convergent and divergent validity were also established. In conclusion, the RCADS is a valid and reliable instrument for assessing anxiety and depression symptoms in Greek adolescents.