The world of drug development is rapidly changing, and one of the most fundamental changes is the increased participation of patients, their families, and their caregivers throughout the process. Historically, pharmaceutical companies and regulatory agencies included participation from patients at limited points during drug development, most often when a drug was nearing approval. Patients’ and caregivers’ knowledge was not routinely included at key points such as targeting early research, assessing the benefits and risks of new therapies, developing regulatory guidelines, or designing clinical trials. This is changing and in this Toolkit, which is part of a series on drug development, we will offer information and case studies that highlight how the patients are using their voices to drive conversations, research and drug development to yield significant advances for their disease communities. For more information about drug development in general or to learn in depth about clinical research, visit From Molecules to Medicine: How Are New Drugs & Therapies Made and From Molecules to Medicine: Clinical Research.