Protists are eukaryotic microorganisms commonly studied due to their ecological relevance in aquatic food chains and their impact on human health. Protistology research and comparative studies are dependent on the accessibility of authenticated biological standards. To meet this need, the Protistology Collection at the ATCC houses the largest and most diverse repository of protist cultures in the world. The primary role of the collection has been the acquisition, authentication, preservation, and distribution of reference strains. Characterization of deposited cultures includes a variety of tests such as viability, purity, phenotypic properties, and genotypic analysis. Additionally, over the last decade, resources within the collection have expanded to include genomic DNA and custom services. This presentation will provide an overview of biological resources available in the ATCC Protistology Collection, a discussion on the methods of characterization, benefits of depositing, current research projects, and future perspectives.