This book contains topics that include: Overview of Hit to Lead: The Medicinal Chemist's Role from HTS Retest to Lead Optimization Hand Off (Christopher A. Lipinski); High Throughput Screening in the 21st Century (Jeff W. Paslay, John E. Morin, and Richard K. Harrison); Lead Discovery Using Virtual Screening (Jack Andrew Bikker and Lakshmi S. Narasimhan); NMR Spectroscopy in Fragment Based Drug Design (Maurizio Pellecchia); Hit Triage - Medicinal Chemistry Strategies to Improve the Odds of Success in Discovery (Kevin D. Freeman-Cook and Daniel W. Kung); and Lead Identification (John W. Ellingboe and Adam M. Gilbert).