Skin, being the primary interface between people and their environment, serves many functions vital to overall health. These functions include protection against pathogens, the blocking of ultraviolet (UV) light, water retention, heat regulation, and sensation, among others.1 Skin forms a barrier around the human body, regulating the entry and exit of all manner of materials. Damage to this barrier not only results in increased transport and potential inammation, but also causes the skin to become aesthetically displeasing. There are various conditions that result in damage to the skin barrier, many of which have etiologies that are only partially understood, making treatment difcult. Most of these conditions exist along a continuum of skin barrier quality. This continuum ranges from self-diagnosed sensitive skin with either no visible damage or only slight inammation to severe eczema exhibiting multiple symptoms including redness, edema, pruritis, crusting, aking, blistering, cracking, oozing, and/or bleeding (Figure 26.1). This chapter will focus on various conditions which involve compromised skin barrier function, as well as current treatments for repairing the barrier and methods to assess the ef- ciency of such treatments.