The National Counterterrorism Center is pleased to present the 2009 edition of the Counterterrorism (CT) Calendar. This edition, like others since the Calendar was first published in a daily planner format in 2003, contains useful information across a wide range of terrorism-related topics: terrorist groups, wanted terrorists, and technical pages on various threat-related issues. The Calendar marks dates according to the Gregorian and Islamic calendars, and contains significant dates in terrorism history, as well as dates that terrorists may believe are important when planning “commemoration-style” attacks.