Originally, the International Academy of Astronautics (IAA) was conceived as a learned society, to be composed of individual members from different countries, who had distinguished themselves in a branch of science of fundamental importance for space exploration. Its Statutes, adopted on 15 August 1960 by the International Astronautical Federation (IAF), as its parent body, established the IAA as one of the activities of the Federation. During the first two decades of its life, the IAA conducted autonomous programs, mostly performed by Academy committees and at the symposia held in the framework of International Astronautical Congresses (IAC). At the beginning of the 1980s, a major improvement of the IAA structure became necessary, to enable the expansion of its programs and impact. A new draft of the Statutes, accompanied by Bylaws, was elaborated and adopted in 1983-1984. The IAA became an independent international nongovernmental organization with its own headquarters in Paris. A series of further amendments to the regulatory basis of the IAA, particularly the establishment of six Academy Commissions that perform their regular programs, led to the present features of the Academy. During the 50 years of its life, the IAA thus passed through a progressive transformation from a multinational learned society to a working, productive, and widely recognized international institution.