DARPA's mission is to maintain the technological superiority of the U.S. military and prevent technological surprise from harming U.S. national security by sponsoring revolutionary, high-payoff research that bridges the gap between fundamental discoveries and their military use. This document provides short summaries of selected DARPA programs in FY 2003 and FY 2004, and it is intended as a ready reference for those interested in DARPA's research portfolio. To better illustrate the goals of the programs, the programs have been grouped into the eight Strategic Thrusts and three Enduring Foundations described in DARPA's Strategic Plan, each with various sub-areas. An index in the back of the document provides assistance in locating individual programs; a table of cross-references to Program Elements in the President's FY 2004 budget appears behind the index. This document is designed to be used in conjunction with DARPA's Strategic Plan (February 2003) , and the Descriptive Summaries in the FY 2004 - FY 2005 Biennial Budget Estimates (February 2003). The Strategic Plan describes, in broad terms, DARPA's current toplevel strategy. The Descriptive Summaries provide more detail on all of DARPA's programs.