Abstract
In adult populations, bipolar disorders (BDs) and posttraumatic stress disorder (PTSD) have overlapping symptoms, potentially leading to misdiagnosis. This misdiagnosis or failure to diagnose both co‐occurring disorders can result in individuals not receiving the proper treatment to address their symptoms. This article highlights how trauma‐informed psychological assessment can assist in differential diagnosis and improve the timely delivery of appropriate treatments. The overlapping symptoms of PTSD and BD are discussed to assist in differential diagnosis, and we suggest guidelines for conducting trauma‐informed, evidence‐based assessments to help clarify these diagnoses.