This document discusses patient engagement in drug development. It defines patients as those with or at risk of a medical condition, along with their families and caregivers. Patient engagement is described as a bi-directional relationship built on principles like partnership and transparency. The document outlines how patients are experts on their disease based on factors like symptoms, quality of life, and treatment experiences. It traces the evolution of patient engagement through different versions of PDUFA (Prescription Drug User Fee Act) and guidance documents from the FDA. The role of patients is described as continuous throughout the drug development lifecycle, from helping design clinical trials to aiding in data interpretation. Different levels of engagement are identified, from being a study participant to leading research