The National Institutes of Health Publication 02-5050, Cancer Clinical Trials: The Basic Workbook, features information about and different aspects of clinical trials. The self-modulated workbook, with its accompanying activities, will help readers understand why cancer clinical trials are important, how they work, how participant safety is protected, as well as some of the reasons so few adults participate in these trials. It is designed for individuals who want to develop a basic understanding of clinical trials. Scientific discoveries are providing more and more insights into the causes of cancer. Many of these successes are limited to the laboratory and have yet to be translated into improved care for people with cancer. Clinical trials are a critical part of the research process. Clinical trials help to move basic scientific research from the laboratory into treatments for people. By evaluating the results of these trials, we can find better treatments and ways to prevent, detect, and treat cancer. But very few adults with cancer-only 3 percent-participate in clinical trials. We need to test the best cancer prevention, detection, and treatment ideas in the shortest time possible, and this can only happen if more people participate in clinical trials. We know that most people understand very little about clinical trials. National Cancer Institute (NCI) research has shown that the general public is either unaware of clinical trials as a treatment/ prevention option or misinformed about the clinical trial process. The reasons for this lack of understanding are complex, and there is no simple solution. We do know, however, that there are many barriers that discourage both physicians and potential participants from taking part in clinical trials. By reading this workbook, you are already helping to overcome some of these barriers. Whether you are a cancer survivor, someone who works with people with cancer, or someone who is touched by cancer in another way-this workbook can help answer your questions about clinical trials. It will help you understand why cancer clinical trials are important, how they work, how the participants' safety is protected, and some of the reasons why more adults don't participate in trials. With this information, you can help people in your community make informed decisions about their cancer treatment and prevention options, including the option of participating in a clinical trial.