Skin cancer is the most common type of cancer, and is also one of the most preventable. This paper builds on an evidence review of skin cancer prevention interventions that was conducted for the Guide to Community Preventive Services (n=85 studies), and summarizes the state of knowledge about research methodology and measurement in studies of the effectiveness of interventions to reduce ultraviolet radiation (UVR) exposure. As this field advances, researchers should strive to minimize threats to validity in their study designs, as well as to consider the balance between internal and external validity. There is a need for more longer-duration interventions, and follow-up periods that make possible conclusions about the potential of these interventions to affect intermediate markers of skin cancer or at least sustained behavior change. Also, more work is needed to minimize attrition and characterize nonresponders and study dropouts. Verbal report measures of behavior are the most widely used measures of solar protection behavior. Given their limitations, investigators should routinely collect data about reliability and validity of those measures. They should also increase efforts to complement verbal data with objective measures including observations, skin reflectance, personal dosimetry, skin swabbing, and inspection of moles. Measures of environments and policies should incorporate observations, documentation, and direct measures of ambient UVR and shade. This article places the data derived from the evidence review in the context of needs and recommendations for future research in skin cancer prevention.