Since World War II, technological arms competition has increasingly militarized international political relations. The reversal of this by arms control and disarmament agreements is largely dependent on the provision of well researched information about what is happening the world military sector from an objective, non-military and neutral source. SIPRI has provided such a source, and this collection of articles celebrating its twentieth anniversary reflects the broad scope of the Institute's studies in the dynamics of armaments, disarmaments, and arms control.These articles summarize the state of play on a wide range of the topics on which SIPRI has focused. These include world military expenditure, military research and development, the arms trade, nuclear weapon stockpiles, nuclear weapon testing, the neutron bomb, the military use of outer space, chemical and biological warfare, nuclear deterrence and nuclear disengagement, the comprehensive test ban, the United Nations and disarmament, and public opinion on peace and war. These papers provide facts and figures, analysis of past trends and future perspectives, and SIPRI's conclusions and recommendations.