Based on a training course developed by Dr. Joseph T. Piechocki and other experts in this field whose contributions appear in this book for two International Meetings on the Photostability of Drugs and Drug Products, this text clarifies the guidelines set by the International Conference on Harmonization (ICH) and provides a comprehensive background in the scientific principles involved in photostability testing. Presenting the advantages and disadvantages of various procedures so the reader can select and utilize the most appropriate technique best-suited to their needs, this source includes references to current literature in the field and offers an opinion on future opportunities and challenges.