Creating a learnable, effective, and user-friendly library Web site hinges on providing easy access to search. Designing a search interface for academic libraries can be particularly challenging given the complexity and range of searchable library collections, such as bibliographic databases, electronic journals, and article search silos. Library Web designers must decide whether to present users with a single search interface--one that searches across content silos by default--or to offer an interface that exposes the various silos available. Designers must also contend with the user's entire search experience and determine how search should appear on the library home page as well as in global navigation systems. In the spring of 2010, the North Carolina State University Libraries sought to answer search design questions for an upcoming Web site design effort. The Libraries evaluated two different search interfaces to determine whether a tabbed search approach with options to pre-select silos is an effective design for end users. Findings show that a tabbed search interface is an effective design device for presenting multiple silos. This study outlines the methods the North Carolina State University Libraries used to conduct usability testing as well as observations, findings, and recommendations about effective design of search on academic library Web sites. (Contains 3 figures and 2 tables.)