Compositions comprising N-acetyl-aldosamines, N-acetylamino acids, and related N-acetyl compounds are useful to alleviate or improve various cosmetic conditions and dermatological disorders, including changes or damage to skin, nail and hair associated with intrinsic aging and/or extrinsic aging, as well as changes or damage caused by extrinsic factors. N-acetyl-aldosamines, N-acetylamino acids, and related N-acetyl composition may further comprise a cosmetic, pharmaceutical or other topical agent to enhance or create synergetic effects.