Increasing public knowledge remains one of the key aims of skin cancer awareness campaigns, yet diagnosis rates continue to rise. It is essential we measure skin cancer knowledge adequately so as to determine the nature of its relationship to sun-related behaviors. This study investigated the psychometric properties of a new measure of skin cancer knowledge, the Skin Cancer and Sun Knowledge (SCSK) scale. A total of 514 Western young adults (females n = 320, males n = 194) aged 18 to 26 years completed measures of skin type, skin cancer knowledge, tanning behavior, sun exposure, and sun protection. Two-week test–retest of the SCSK was conducted with 52 participants. Internal reliability of the SCSK scale was acceptable (KR-20 = .69), test–retest reliability was high (r = .83, n = 52), and acceptable levels of face, content, and incremental validity were demonstrated. Skin cancer knowledge (as measured by SCSK) correlated with sun protection, sun exposure, and tanning behaviors in the female sample, but not in the males. Skin cancer knowledge appears to be more relevant to the behavior of young women than that of young males. We recommend that future research establish the validity of the SCSK across a range of participant groups.