This document is the implementation plan for the Information Technology for the 21st Century (IT[squared]) initiative. With this initiative, the Federal Government is making an important re-commitment to fundamental research in information technology. The initiative proposes $366 million in increased investments in computing, information, and communications research and development (R&D). Six agencies--all highly dependent on advances in information technology--are participating in the initiative: Department of Defense (DoD) (including the Defense Advanced Research Projects Agency [DARPA]); Department of Energy (DOE); National Aeronautics and Space Administration (NASA); National Institutes of Health (NIH); National Oceanic and Atmospheric Administration (NOAA); and National Science Foundation (NSF). Each agency will bring its own unique mix of capabilities and expertise to bear on an appropriate subset of the R&D objectives of the initiative. The initiative will extend existing R&D and provide opportunities to address new, complementary R&D topics in three key areas: long term information technology R&D leading to fundamental advances in computing and communications; advanced computing infrastructure to facilitate scientific and engineering discoveries of national interest; and research on the economic and social implications of the Information Revolution, and the training of additional information technology workers at universities. Details for each of these areas are presented in three sections of this report, with each section providing an introduction and strategy and descriptions of specific agency efforts. A final section presents the management plan, outlining IT[squared] interagency management objectives and management structure; general implementation guidelines; reporting; and the President's Information Technology Advisory Committee (PITAC) and other external advisory groups. A table at the beginning of the report shows the proposed IT(squared) fiscal year 2000 budget, in millions of dollars, for each agency and each of the three key areas. (AEF)