Statistical methods for clinical trials have been an area of active research in Biostatistics since the first modern clinical trials were mounted in 1946 by the British Medical Research Council in whooping cough and tuberculosis. Often, the participants in clinical trials suffer from potentially fatal chronic diseases, and it is especially important that these experiments in medical research use designs that are efficient, can be understood by physicians, policy makers and patients, respond quickly new ideas in medicine and statistics, and, perhaps above all, show respect for the complex and important ethical issues that arise in these settings. This book explores some recent thinking in designs for clinical trials, including alternative designs for phase I studies, interim monitoring for futility, adaptive designs based on accumulating outcome data, and designs of new, targeted therapies. The book is intended for both the statistical practitioner, who may be too busy to stay abreast of the literature on statistical methods, as well as statisticians conducting research in clinical trials.