Skin cancer is a major public health issue with global rates of disease steadily on the rise. Intentional tanning behaviors, including sunbathing and indoor tanning, are high-risk practices strongly associated with an increased risk of skin cancer. Despite the known health risks, both indoor and outdoor tanning remain popular, particularly among young adult non-Hispanic white women. While all tanning increases the risk of skin cancer, in a subset of those who tan the behavior becomes frequent and excessive, with addiction-like properties. “Tanning addiction” is thus associated with the characteristics of other addictions such as craving for the behavior, a reinforcing effect, an inability to quit, and resulting adverse health consequences related to the behavior. Motivations driving tanning addiction may stem from both psychological factors such as appearance norms and from the physiologic effects of exposure to ultraviolet light on brain reward pathways influencing mood. In this chapter we present the concept of tanning as an addiction, reviewing its definition, measurement, and prevalence in the population, and outlining the empirical evidence for the behavioral and biological drivers of tanning addiction. The implications of this research, we suggest, warrants greater attention to this emerging addiction, and necessitates the development of effective prevention and treatment interventions in those at risk of addictive tanning.