BACKGROUND: Extensive print, radio, and television coverage about the dangers of sun exposure and benefits of sun protection occurred over the past decade. Illinois teen knowledge and attitudes about sun exposure/protection, sun-exposure/protection behavior, and information sources were determined by a summer telephone survey. METHODS: Telephone interviews with 658 teenagers between ages 11 and 19 included African-American, Asian, Hispanic, Native American, and white teenagers. RESULTS: Teens knew that too much sun was harmful as it caused skin cancer and sunburn. Sunburn was mentioned more often by those with skin types that burned easily and tanned poorly (I,II) (P < 0.001), was better known to girls than to boys (P < 0.001), and was recognized more by those with higher socioeconomic status (P < 0.001) but was not associated with age. Widely held sun exposure attitudes were socializing with friends and feeling better when outdoors. On weekdays, boys averaged 5.3 hr (SD, 1.65 hr) outside compared with 3.9 hr (SD, 0.75 hr) for girls (P < 0.001). Teenage boys were more likely to obtain occupational sun exposure, and girls sunbathed. Subjects with skin types I and II reported an average of 3.3 sunburns in the past year. During unprotected sun exposure, extensive numbers of teens with moderate-risk skin type experienced at least 1 sunburn per year. Indoor tanning use was more prevalent among older girls and those with skin types I and II. Sunscreen use was associated with water recreational activities (swimming, water sports, and going to the beach) by girls slightly more than by boys (P < 0.001). Hat-wearing was more common among boys than among girls. CONCLUSIONS: Teen knowledge that excessive sun exposure causes skin cancer and sunburns and that wearing sunscreens and hats were sun-protective methods did not enable sun protection that prevented burning. This is particularly troublesome because severe sunburns in youth are associated with an increased risk of melanoma. Existing teen sunscreen use could be broadened by educating teens to use adequate quantities of sunscreen prior to daily sun exposure to prevent painful burns. Messages to teens that emphasize the short-term consequence of painful sunburns because of inadequate protection during outdoor occupational and non-water-related recreational exposure would increase the relevance of the message and may enable behavioral change. Parents and physicians need to be included in messages that are directed to teens and to become part of their education. Parents could ensure an adequate sunscreen supply for daily use by the family, encourage teens not to deliberately tan, and serve as role models for the use of protective clothing.