The Rapid Mood Screener (RMS) is a screening tool that was developed to differentiate bipolar I disorder from major depressive disorder (MDD) in patients with depressive symptoms who have been diagnosed with MDD. Created by a team of multidisciplinary experts including primary care clinicians, psychiatry nurse practitioners, psychiatrists, pharmacists, behavioral therapists, psychometricians, and health economists, the RMS provides a pragmatic approach to addressing the need for easy and accurate screening of bipolar I disorder.