Background: The incidence of skin cancers is steadily increasing. In particular,because children and adolescents tend to be outdoors during the hours of mostintensive sunlight, schools play an important role in establishing sun protectionbehavior among students.Purpose: The aim of this research was to investigate the effect of a Sun ProtectionProgram (SPP) on the sun protection behavior of Turkish adolescents.Methods: This study was designed as pre-/posttest control group semi-experimentalresearch. The research was carried out with 147 12-15 years-old adolescents in twoschools. One of the schools was randomly designated as consisting of the interventiongroup of students; the other represented the control group. The intervention groupcomprised 76, the control group 71 students, which together made up the sample.Covariants were calculated in the pre-test scores and covariance analysis performedto evaluate the impact of the intervention on both groups. The SPP formed the basisfor the program and consisted of 6 posters, a 12-page student handbook, 4 puzzles,educational videos, and a UV-sensitive Frisbee game.Results: The intervention group’s sunscreen use stage of change and sun avoidance,using sunscreen and hat self-efficacy mean scores were higher and statistically moresignificant than in the control group (p<.001). In addition, the increase in the scoreson the posttest as compared to the baseline in the sunscreen stage as well as in thepros scores was found to be significant in the intervention group but not in the controlgroup (p<.05).Conclusion: The study showed that a school-based SPP was effective in the shortterm in achieving progress in the Transtheoretical Model (TTM) sunscreen usestages, perceiving pros and in sun avoidance, sunscreen and hat use self-efficacy,meaning that the program may be used in schools to increase sun protection behavior.School-based, nurse-led, short-term studies encompassing group interventions aresuccessful in developing sun protection attitudes and will be useful in the future in thecontext of school nursing activities.