Background: Indoor tanning is a popular behavior that may increase skin cancer risk. Objective: To examine characteristics associated with use or intention to use indoor tanning among adolescents. Methods: A telephone interview was conducted with 1273 adolescents, aged 14 to 17 years, in the Minneapolis-St Paul, Minn, and Boston, Mass, metropolitan areas. Questions included demographic and phenotypic characteristics, knowledge, attitudes, social factors, use of indoor tanning, and intention to tan indoors. Results: Twelve percent of boys and 42% of girls had tanned indoors. Among nontanners, 22.4% planned to start, and 77.2% of tanners planned to continue tanning indoors. Nontanners and tanners at risk for future indoor tanning use were each significantly more likely to be female, less likely to use sun protection, less knowledgeable about skin cancer risks, more likely to agree that tans were attractive, and more strongly influenced by social factors compared with their low-risk counterparts. Conclusions: Our data suggest that intention to tan indoors may identify a group of adolescents at risk for adopting the behavior; prospective studies are needed for confirmation.