In order to better understand drivers of dangerous indoor tanning behaviors, researchers developed the Comprehensive Indoor Tanning Expectations scale. To examine the longitudinal effectiveness of Comprehensive Indoor Tanning Expectations, we surveyed young women in the Southeastern United States at two time points (N = 553). The scale demonstrated strong test–retest reliability. Participants who believed indoor tanning would improve their mood and afford social approval were significantly more likely to tan 6 months later, while participants who believed indoor tanning leads to psychological/physical discomfort were significantly less likely to tan 6 months later. Knowing the psychological bases for indoor tanning can inform intervention and message design.