The present study reports on the psychometric defensibility of the Psychological Wellbeing and Distress Screener (PWDS), which is a 10-item self-report behavior rating scale for measuring youth's bidimensional (also known as dual-factor or two-continua) mental health. The PWDS was developed using preexisting items within the Health Behavior in School-Aged Children (HBSC) self-report survey, and the present study used the 2009-2010 HBSC sample of U.S. youth in Grades 5 to 10 (N = 12,642). Findings from two phases of data analyses, using random split-half subsamples, identified and confirmed a two-factor latent structure for the PWDS, with one scale measuring psychological wellbeing and the other psychological distress. Results also showed that the wellbeing and distress factors were invariant across grade, race/ethnicity, and residence classifications but not across gender. Implications for future research and potential practice are discussed.