A growing body of literature suggests that some moisturizers can improve stratum corneum barrier function, as well as ameliorate dry skin. The clinical signs and symptoms of rosacea, which include increased facial skin dryness and sensitivity, suggest a possible role for such moisturizers as an adjuvant in the management of this condition. This randomized, investigator-blind, controlled observational study (N = 50) was designed to assess whether a niacinamide-containing facial moisturizer would improve the stratum corneum barrier and thus provide a clinical benefit to subjects with rosacea. Subjects with rosacea applied the test moisturizer to their face and to one forearm twice daily for 4 weeks. The other forearm remained untreated as a control. Barrier function on the forearms was assessed instrumentally and using a dimethyl sulfoxide (DMSO) chemical probe. Stratum corneum hydration also was measured instrumentally. The dermatologist investigator evaluated each subject's rosacea condition over the course of the study, and subjects self-assessed their facial skin condition at study end. Instruments provided objective measures of stratum corneum barrier function and hydration on the face.