In the United States, the Dietary Supplement Health and Education Act of 1994 (DSHEA) classified dietary supplements as a subcategory of food, exempting manufacturers from providing premarket evidence of product safety and efficacy. Under DSHEA, agencies such as the U.S. Food and Drug Administration (FDA) cannot inspect supplements until after the products have entered the marketplace. Recognizing that both limited resources and DSHEA prevent the FDA from conducting broad-based inspections on a regular basis, disreputable manufacturers have spiked products with drugs such as anabolic steroids and amphetamines. With contaminated supplements now causing athletes to fail drug tests and, in some instances, threatening public health, it becomes important to examine sources of supplement information. This article reviews 53 studies that have addressed athlete information sources about dietary supplements. It finds that athletes, in general, rely heavily on coaches and trainers as well as friends and family for information. Relative to U.S. athletes, those competing internationally appear more likely to seek information from a physician or nutritionist. The article offers recommendations for individuals and organizations based on the most frequent information sources identified by athletes.