The preschool is an important yet understudied setting for sun-protection interventions. This study evaluates the effects of Sun Protection is Fun! (SPF) on preschool staff behavioral and psychosocial outcomes related to protecting children from sun exposure. Twenty preschools participated in a 2-year, group-randomized trial to evaluate SPF, a behavioral intervention grounded in social cognitive theory and designed to be more extensive than previous preschool sun-protection interventions. The staff intervention included training, a video, newsletters, a curriculum, and sunscreen. Cross-sectional samples of staff completed surveys at baseline (N= 245), a 12-month intervention assessment (N = 192), and a 24-month intervention assessment (N = 225). At the 12-month and 24-month assessments, significant behavioral effects were seen for use of sunscreen, protective clothing, and shade. Knowledge, self-efficacy, and norms were among the psychosocial variables most affected by the intervention. This study demonstrates that the SPF intervention is effective in improving staff outcomes related to children's sun protection. (Contains 4 tables.)