[en] This, second in a new series of booklets dealing with IAEA safeguards is intended for persons professionally interested in the subject as government officials responsible for non-proliferation or management of nuclear facilities, and practitioners of safeguards - the international and national officials charged with implementing IAEA safeguards. It is also aimed at the broader public concerned with the spread of nuclear weapons and interested in nuclear arms control and disarmament. It presents the situation as IAEA safeguards make 'quantum jump' into new phase characterized by the IAEA as the 'Strengthened Safeguards System'. It includes the historical overview of the International safeguards from 1945-1998; the aims and limitations of IAEA Safeguards; a chapter on how safeguards work in practice; as well as new challenges and opportunities