General Background.- 1 Cosmetic Claim Substantiation in the United Legal Considerations.- 2 The Contribution of the European Cosmetics Directive Towards International Impact on the Evaluation of Safety and Efficacy.- 3 Claim Support in Legal Aspects.- 4 Claim Ethical Aspects for Conducting Human Studies.- Efficacy.- 5 In Vivo Evaluation of the Hydration State of the Measurements and Methods for Claim Support.- 6 Oily Claim Support Strategies.- 7 On the Problems of In Vivo Cleansing of the Human Skin.- 8 Methods for Antiperspirant and Deodorant Efficacy Evaluations.- 9 Sunscreens.- 10 Self- or Sunless Tanning Lotions.- 11 Anti-Dandruff.- 12 Efficacy of Barrier Creams (Skin Protective Creams).- 13 Anti-Cellulite.- 14 Methods for Claim Support in Hair Cosmetics.- 15 Racial Differences in Skin Related to Claim Support.- 16 The In Vivo Biomechanical Testing of the Skin and the Cosmetological Efficacy Claim A Critical Overview.- 17 Skin Gloss Metry.- Safety.- 18 Hypoallergenic Cosmetics.- 19 The Use of Sensitive Skin Panels to Substantiate Cosmetic Claims.- 20 Fragrances Between Allergic, Hypoallergic, and In Vitro Studies.- 21 Contact Urticaria Syndrome (CUS) and Claims Support.- 22 Photoreactions.- 23 Comedogenesis.- 24 Antimicrobial and Preservative Efficacy.- 25 Mutagenicity.