With the publication of Terrorism: Commentary on Security Documents, Index IV, Oxford University Press continues to provide periodic stand-alone volumes containing cumulative indexes for the individual volumes in the series. Index IV (covering Terrorism Vols. 101-120) adds to the previous index volumes in order to ensure comprehensive searchability within the series. The availability of the cumulative index as well as the volume-specific indexes makes the series more convenient for the reader and provides the researcher with multiple ways to search for information. Index IV also features improved double-columned index formatting, for ease of use in a more compact volume. Although each volume in Terrorism: Commentary on Security Documents contains its own volume-specific index, this comprehensive index fully indexes the last twenty volumes in the Terrorism series. Only subject indexes are included in the individual volumes, whereas this comprehensive index includes five different types of indexes including a subject index, an index organized according to the title of the document, an index based on the name of the document's author, an index correlated to the year of the document, and a subject-by-year index. This cumulative index volume therefore provides readers with multiple ways to conduct research within Volumes 101-120 of Terrorism: Commentary on Security Documents.