The American Association for the Advancement of Science (AAAS) is a United States–based international nonprofit with the stated mission of promoting cooperation among scientists, defending scientific freedom, encouraging scientific responsibility, and supporting scientific education and science outreach for the betterment of all humanity. AAAS was the first permanent organization established to promote science and engineering nationally and to represent the interests of American researchers from across all scientific fields. It is the world's largest general scientific society, with over 120,000 members, and is the publisher of the well-known scientific journal Science.

The American Association for the Advancement of Science was created on September 20, 1848, at the Academy of Natural Sciences in Philadelphia, Pennsylvania. It was a reformation of the Association of American Geologists and Naturalists with the broadened mission to be the first permanent organization to promote science and engineering nationally and to represent the interests of American researchers from across all scientific fields The society chose William Charles Redfield as their first president because he had proposed the most comprehensive plans for the organization. According to the first constitution which was agreed to at the September 20 meeting, the goal of the society was to promote scientific dialogue in order to allow for greater scientific collaboration. By doing so, the association aimed to use resources to conduct science with increased efficiency and allow for scientific progress at a greater rate. The association also sought to increase the resources available to the scientific community through active advocacy of science. There were only 78 members when the AAAS was formed. As a member of the new scientific body, Matthew Fontaine Maury, USN was one of those who attended the first 1848 meeting.

At a meeting held on Friday afternoon, September 22, 1848, Redfield presided, and Matthew Fontaine Maury gave a full scientific report on his Wind and Current Charts. Maury stated that hundreds of ship navigators were now sending abstract logs of their voyages to the United States Naval Observatory. He added, "Never before was such a corps of observers known." But, he pointed out to his fellow scientists, his critical need was for more "simultaneous observations". "The work," Maury stated, "is not exclusively for the benefit of any nation or age". The minutes of the AAAS meeting reveal that because of the universality of this "view on the subject, it was suggested whether the states of Christendom might not be induced to cooperate with their Navies in the undertaking; at least so far as to cause abstracts of their log-books and sea journals to be furnished to Matthew F. Maury, USN, at the Naval Observatory at Washington."^{[citation needed]}

William Barton Rogers, professor at the University of Virginia and later founder of the Massachusetts Institute of Technology, offered a resolution: "Resolved that a Committee of five be appointed to address a memorial to the Secretary of the Navy, requesting his further aid in procuring for Matthew Maury the use of the observations of European and other foreign navigators, for the extension and perfecting of his charts of winds and currents." The resolution was adopted and, in addition to Rogers, the following members of the association were appointed to the committee: Professor Joseph Henry of Washington; Professor Benjamin Peirce of Cambridge, Massachusetts; Professor James H. Coffin of Easton, Pennsylvania, and Professor Stephen Alexander of Princeton, New Jersey. This was scientific cooperation, and Maury went back to Washington with great hopes for the future.

In 1850, the first female members were accepted: astronomer Maria Mitchell and entomologist Margaretta Morris. Science educator Almira Hart Lincoln Phelps was elected in 1859.

By 1860, membership increased to over 2,000. Although the AAAS became dormant during the American Civil War (their August 1861 meeting in Nashville, Tennessee, was postponed indefinitely after the outbreak of the first major engagement of the war at Bull Run), the association recovered after the end of the hostilities.

In 1866, Frederick Barnard presided over the first meeting of the resurrected AAAS at a meeting in New York City. Following the revival of the AAAS, the group had considerable growth. The AAAS permitted all people, regardless of scientific credentials, to join. The AAAS did, however, institute a policy of granting the title of "Fellow of the AAAS" to well-respected scientists within the organization.

At the same time, the recovered AAAS faced competition from several newly established learned societies, such as National Academy of Sciences (founded in 1863), the American Chemical Society (1876), Archaeological Institute of America (1879), Modern Language Association (1883), American Historical Association (1884), Geological Society of America (1888), National Geographic Society (1888), American Physical Society (1899), which drew away some of AAAS members. Also, the reputation of the AAAS was somewhat tarnished, because its 3rd president Alexander Dallas Bache used the Society as a lobbying tool for his agency, the US Coast Survey. Several prominent scientists lost interest in the AAAS, and the society's influence declined.