The three major types of skin cancer are melanoma, squamous cell carcinoma, and basal cell carcinoma. There are four major subtypes of cutaneous melanoma: superficial spreading, nodular, lentigo maligna, and acral lentiginous. Some melanomas are not easily classified into a single category and may have overlapping features. Skin cancer is the most common cancer in the United States. Over 1 million persons are diagnosed annually in the United States with cutaneous malignant melanoma, squamous cell carcinoma, or basal cell carcinoma. While melanoma is less common than basal cell and squamous cell carcinoma, it is also more deadly. Incidence rates of melanoma have also been increasing worldwide. Several factors may contribute to increasing incidence rates, including increased exposure to carcinogenic factors (i.e., ultraviolet [UV] exposure), increased public awareness of the warning signs of melanoma, and increased screening by clinicians. Mortality rates are more than 5-fold lower than incidence rates, but depend upon stage at diagnosis. Of the approximately 1.3 million cases of skin cancer diagnosed each year, about 800,000 to 900,000 are basal cell carcinoma, and 200,000 to 300,000 are squamous cell carcinoma. While squamous cell cancer accounts for less than 0.1 percent of all cancer deaths, it does have the potential to metastasize and may account for a significant proportion of mortality from skin cancer in older persons and immunosuppressed persons. In contrast, survival rates for those with basal cell carcinoma are indistinguishable from those of the general population. On the basis of mortality, squamous cell and basal cell carcinoma are often not considered important problems. Because of their high and rising incidence, however, squamous cell and basal cell carcinoma pose a significant economic burden. This report was written to support the U.S. Preventive Services Task Force (USPSTF) in updating its 2003 recommendation on counseling for skin cancer prevention. The 2003 report found a single counseling trial, in the context of a community-based educational intervention, that examined the effectiveness of increasing sun-protective behaviors. Given the multimodal nature of this intervention, however, the contribution of the office-based counseling component could not be isolated. In addition to the counseling literature, the previous report also examined the association between sun-protective behaviors and melanoma. This report found that determining the efficacy of sun avoidance and use of protective clothing for the prevention of melanoma is complex. The evidence did support the hypothesis that intermittent sunburn in childhood is a preventable risk factor. However, no trials linking sun avoidance or use of protective clothing to a decrease in skin cancer incidence were identified. Finally, the report found one trial showing a modest benefit of sunscreen in preventing squamous cell carcinoma. This review focuses on new trial evidence for counseling interventions to prevent skin cancer conducted in primary care, and also reexamines previous trials that were not conducted in primary care but may be considered feasible for primary care adoption or represent community interventions to which primary care can refer patients. The early detection of skin cancer with skin self-examination is addressed in the recently updated evidence review on skin cancer screening.3 This review also examines the harms directly associated with counseling interventions, epidemiologic associations between key behaviors in counseling interventions (i.e., decreased sun exposure, sunlamp or tanning bed avoidance, and sunscreen use) and relevant skin cancer outcomes, and the potential harms associated with these sun-protective behaviors.