The present studies report on the initial development and validation of the Youth Internalizing Problems Screener (YIPS), which is a 10-item self-report rating scale for assessing general internalizing problems and identifying depression and anxiety caseness within the context of school mental health screening. Results from Study 1 (N = 177) demonstrated that responses to the YIPS yielded a single-factor latent structure, that scores derived from the scale had concurrent validity with scores from measures of student subjective well-being and problem behavior, and showed that scores derived from the YIPS demonstrated incremental validity in comparison with scores from another common internalizing problems screener for predicting self-reports of broad student functioning. Findings from Study 2 (N = 219) confirmed the latent structure and internal reliability of responses to the YIPS, demonstrated that scores derived from this scale had strong associations with scores from criterion measures of depression and anxiety, and showed that YIPS scores had good-to-excellent power for accurately discriminating between youth scoring at or above the clinical caseness thresholds on criterion measures of depression and anxiety. Taken together, results suggest the YIPS shows promise as a technically adequate instrument for measuring general internalizing problems and identifying depression and anxiety caseness among secondary students. Implications for future research and practice are discussed.