Toward More Effective Science and Technology Advice for Congress traces the historical roots of science and technology advice for Congress and chronicles the creation and evolution of the four organizations that provided this advice over the past half century -- (1) the National Research Council, (2) the Congressional Research Service, (3) the former Office of Technology Assessment, and (4) the Government Accountability Office. Key characteristics for providing effective S&T advice for Congress are defined and then used to evaluate the relative strengths and weaknesses of these organizations today and to identify prospective organizational improvements in each to meet today’s needs.