Cosmetic products are broadly defined as agents that can improve the skin's appearance, and moisturizers fall within this definition. The ability of modern moisturizers to improve skin condition and appearance is widely recognized, especially since the effects of such products can be perceived by the consumer and measured using a variety of clinical techniques. In this chapter the potential benefits of moisturizers for both skin dryness and photoaging are discussed, as well as the means by which these benefits may be measured.