The first objective of this study was to analyze the differences between adolescents who use sunscreen frequently and those who do not. The second objective was to explore the importance of specific action plans when planning sunscreen use. Data was gathered among 602 Belgian secondary school students. Frequent and infrequent users of sunscreen were compared on several determinants related with sunscreen use, and a regression analysis on sunscreen use was done. Frequent users of sunscreen measures had significantly higher scores on attitudes, social influence, self-efficacy, some awareness factors, intention, and action plans. The integrated model for exploring motivational and behavioral change (I-Change model) explained 57% of the total variance of using sunscreen every 2 hours. Frequent sunscreen use was most strongly predicted by action plans, followed by positive intentions to use sunscreen, wearing protective clothing, seeking shade, attitude toward sunscreen use, education, social influence, and exposure to the sun. Our results suggest that skin cancer prevention programs aimed at promoting sunscreen use need to emphasize the advantages of sunscreen to infrequent users and to increase feelings of self-efficacy. Moreover, support by friends and parents should be stimulated. Finally, developing specific action plans for the use of sunscreen should be promoted to more effectively translate general intentions into actual sunscreen use. (Cancer Epidemiol Biomarkers Prev 2006;15(7):1360 -6)