Another topic that is clearly of interest today is the replacement of animal testing by alternative methods for testing the safety of cosmetic ingredients. The cosmetic industry, by separate activities or via its association, the COLIPA (The “European Cosmetic, Toiletry, and Perfumery Association”), has been extremely active in developing in vitro methods and strategies for confirming the safety of their ingredients. Even if much work has still to be done, great progress has been realized. Some updates on method developments are described in this book, although it has not been possible to cover all of them.