This review of OAIster investigated the utility of OAIster as a tool for library users to discover and access relevant information. Because the vision for OAIster is so large, one goal of this review was to describe OAIster based on reviewing search results. FirstSearch, OAIster.worldcat.org, and EBSCO Discovery Service interfaces were reviewed. Five searches were performed in each interface, and the material types and counts were recorded. Because OAIster is intended to link only to publicly accessible resources, links to resources were also tested. The review found large differences across interfaces in the number of results, classification of records into material types, and access to resources. Discovery tools do not always map OAIster metadata effectively, and public search engines do not seem to thoroughly index OAIster. Some OAIster records link to non-full-text or not publicly accessible resources. OAIster is a valuable tool for discovering resources in archives, special collections, and institutional repositories, but its place among Open Access search tools is still somewhat unclear. pricing options OAIster is an Open Access database and its native interface is open to the public. Institutions and consortia can also access OAIster through discovery services such as EBSCO Discovery Service, and OAIster is available to OCLC FirstSearch Base Package subscribers. OCLC intends to replace FirstSearch by the end of the calendar year; First-Search libraries and content will all be transitioning to WorldCat Discovery. 1 WorldCat Discovery was not available to us at the time of testing or writing this article, so we were unable to compare within that interface. product description Describing OAIster is challenging. The official product description is somewhat vague: OAIster is a union catalog of millions of records representing Open Access resources that was built by harvesting from Open Access collections worldwide using the Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH). Today, OAIster includes more than 30 million records representing digital resources from more than 1,500 contributors. 2 An OCLC representative noted that OAIster records "should only describe materials that are Open Access and therefore accessible online," but that OCLC does not currently have an automated process to proactively "ensure that OAIster records that have URLs always link The Charleston Advisor / April 2015 www.charlestonco.com 5