Arthropod bites and stings are ubiquitous. The majority of exposures are related to outdoor activities. Such outdoor exposures occur at all ages, with no unique predilection for adolescents. Reactions may range from a minor nuisance to severe and life-threatening conditions. Photosensitivity reactions are far less common and often difficult to diagnose. Outdoor activities predispose teens to a variety of cutaneous maladies, including three specific photosensitivity disorders that are often seen in adolescents and young adults: polymorphous light eruption, actinic prurigo, and hydroa vacciniforme. Many other genetic and inflammatory conditions cause photosensitivity but are beyond the scope of this chapter.