How do archives provide access to their records and let users search? The answer is archival description. Encoded Archival Description (EAD) in Extensible Markup Language (XML) is the de facto technical standard for 'electronic' archival descriptions. It is now used to bridge the gulf between tangible records in archives and digital objects on the World Wide Web. These descriptions are finding aids, which are tools to search and find information about, or references to, archival records. The archival finding aids in EAD are left to searchers (out of sight and contact) to explore in unknown ways: how do searchers interact with these finding aids, and what type of retrieval system is needed to support them?The approach is to apply XML retrieval techniques to the EAD finding aids, develop system evaluation of EAD retrieval, and study information seeking behavior of archival search. The main information retrieval (IR) contributions are the system evaluation of an important 'real' and domain-specific search task, a study on the usage of transaction logs for deriving domain-specific test collections, an analysis of search behavior in yet unexplored structured documents, and tailoring IR evaluation to specific searcher stereotypes.The first study involves the design and implementation of the archival search engine README. The README system attempts to incorporate current technologies with the archival structure in finding aids-such as XML retrieval-and simultaneously to uphold the archival principles where this structure is based upon. The system is the proof of concept.Having established this baseline, the next study explores and tests the construction of an IR test collection. A test collection is a key component in IR evaluation. The basis of this test collection are the queries and clicks on archival descriptions that can be found in the search log files of the National Archives of the Netherlands. There is no readily-available test collection for evaluating the accuracy of the retrieval of archival descriptions of records by an archival search engine. Manually creating such a collection is expensive. The study shows that automatically creating a test collection seems viable.Archival principles-such as provenance and original order-are deeply rooted in the arrangement and subsequent description of archival records. These principles have been cast on EAD finding aids as well. The investigation continues by shedding new light on them in a system evaluation. Additionally, the experiments probe XML retrieval-specific issues, such as the retrieval of certain elements. The study concludes by reflecting on the README
