The International Lithosphere Program is a new international interdisciplinary research program in the solid earth sciences that has been established by the International Council of Scientific Unions (ICSU) at the joint request of the International Union of Geodesy and Geophysics (IUGG) and the International Union of Geological Sciences (IUGS). Its goal is a better understanding of the development of the earth, particularly those aspects upon which human society depends for its well‐being.The International Lithosphere Program (ILP) is a natural sequel to a series of international cooperative projects in the geosciences that began with the International Geophysical Year in 1957–58 and continued with the Upper Mantle Project in the 1960's and the International Geodynamics Project (IGP) in the 1970's. In 1977, IUGG and IUGS established an inter‐union task group to consider the possibility of a successor to the IGP for the 1980's. The task group, under cochairmen Carl Kisslinger (Cooperative Institute for Research in Environmental Sciences, University of Colorado), foreign secretary of the American Geophysical Union, and J. Henning Illies (Geophysical Institute, University of Karlsruhe, Federal Republic of Germany), invited suggestions and comments from the two unions and the national committees in the member countries. Their report, which was completed late in 1978, proposed a new project on the dynamics, origin, and evolution of the lithosphere. This proposal was approved by the IUGS Executive Committee in December 1979 and by the IUGS Council in June 1980. An inter‐union steering committee, established in 1979 under the joint chairmanship of Kisslinger and Illies, developed the organizational framework and constitution of the new program. These were approved by resolution of the ICSU Governing Board in September 1980, and the Inter‐Union Commission on the Lithosphere (ICL) was established to implement the program. National members of ICSU were urged to establish national committees and to develop internal programs for the new International Lithosphere Program.