The United States Pharmacopeia (USP) is an independent, nonprofit science-based organization whose mission is to improve global health through public standards and related products for medicines, food and dietary supplements. Probiotic-based dietary supplements are increasingly popular in the marketplace and USP has developed fourteen monographs specific to probiotic ingredients, including representatives from the Genera Lactobacillus, Bacillus, Streptococcus, and Bifidobacterium. These monographs include the definition of the article, tests for identification, quantification assays (enumeration in the case of probiotics), limits for contaminants, and other quality parameters when appropriate. In addition to quality, the USP also considers the safety of probiotics for monograph development. This report includes an overview of the USP admission evaluation process for probiotics as well as a tabular summary of the probiotic monographs currently available. Pharmacopeia monographs can guide manufacturers and brand owners and protect consumers through establishment of quality standards.