Welcome to the Health for All website The Health for All website is a tool to help you learn more about clinical trials and preventive services. You can find a clinical trial here and information on preventive services here. Find more resources at the Chicago Public Library. Click on a question below to learn more What is a clinical trial? Why should I trust clinical trials? What are pros and cons of being in a clinical trial? Why does diversity matter in clinical trials? Why join a clinical trial if I’m healthy?