Diagnostic error in medicine affects approximately 12 million patients each year. This session will cover key concepts in clinical reasoning, how we make errors, and methods to address these challenges. We will define and discuss problem representations, illness scripts, dual-process theory, cognitive biases and other major topics in this field. As a group, we will reason through a clinical case, focusing on the diagnostic process, and perform a cognitive autopsy afterwards. Additionally, this session will overview a curriculum design for residency programs to teach clinical reasoning to residents and medical students.