At the Web 2.0 Summit in San Francisco 2007,investment bank Morgan Stanley stated that UnitedStates businesses spend 50% of their capitalexpenditure on information technology. Given such amassive investment, the performance of the US economydepends very heavily on the extent to which USbusinesses and their workers use these investments ininformation technology wisely. This book is driven bya question that is often asked by organizations: whatcan we do to maximize the benefits of IT? Thisresearch approaches this question from a human agencyperspective: IT does not determine its own trajectoryof development and use. It is users who create andinnovate its evolution. This book investigates how individual users modifytheir use of information systems adaptively over timeto respond to external and internal triggers, withincertain constrains. A new concept named adaptive ITuse was developed. A model of adaptive IT use thatdepicts and explains the scenario of usermodifications to their use of information systems wasdeveloped systematically. The research hassignificant implications for both research andpractices in system development and implementation.