Librarians are familiar with the single-line form, the consolidated index, which represents a very large portion of a library's print and online collection. Their end users are familiar with the idea of a single search across a comprehensive index that produces a large, relevancy-ranked results list. Even though most patrons would not recognize the term web-scale discovery (WSD), it is what they have come to expect. More and more libraries are stepping up to meet their users' expectations by implementing WSD services. Librarians around the world are trying to learn what these services are and how they work, evaluating the services on the market, selecting and implementing a service, and then teaching colleagues and patrons all about it. Based on her efforts to evaluate today's highly touted web-scale discovery systems, the author shares tips for evaluating the various services that are out there, based on her work in selecting a web-scale solution for the University of Central Florida.