Sun protection in childhood is important to reduce the risk of developing skin cancer later in life. The “Periods- of-Life-Program” for primary prevention of skin cancer intro- duces a combination of individual and environmental interventions for the preschool period. Within this pilot study, an intervention group received cognitive–behavioral and environmental interventions. A control group had solely received the environmental intervention, and a wait–control group received no intervention. Nursery school children (n = 80, 3 to 6 years of age) of four nursery schools were randomly assigned to these groups on school level. The ability of the cognitive–behavioral intervention (a theater play) to enhance sun protection knowledge was examined. The theater play improved knowledge over all age groups (p < .05 η2 = .06). Age-specific analyses showed better results for children aged 5 to 6 (p<.05 η2 =.20) compared to children aged 3 to 4 years (p=.17 η2=.04). In combining cognitive–behavioral and environmental interventions, the “Periods-of-Life-Program” is a promising strategy for primary prevention of skin cancer.