Since its founding in 1863, the National Academy of Sciences (NAS) has occupied a special niche in the complex ecology of advice-giving in the United States. Established as a small, private organization with special responsibilities and obligations vis a vis the American people and government, the Academy has expanded considerably in the past century and a half and now releases, through the National Research Council (NRC), its operating arm, more than 200 reports per year, on topics covering nearly the entire range of science, engineering, health, and education. The development of the organization, its basic ethos, and its evolving structures and processes can be seen as examples of what Herbert Simon called "procedural rationality": the pursuit of reasonably good solutions to complex problems based on appropriate deliberation.