Stem cells can propagate indefinitely in an undifferentiated state; or, with appropriate signals, differentiate into various types of mature cells. Strong interest in stem cell therapies for degenerative diseases has extended to skin aging, itself a degenerative process. This article reviews mechanisms of skin aging, and enables an evidence-based approach to topical skin rejuvenation - specifically, to formulations labeled as stem cell products. J Drugs Dermatol. 2017;16(4):378-384. .