Imam Mahdi will rise in the last days of the world to fill the earth with justice. According to Shi'i beliefs, the twelfth Imam is Muhammad ibn Hasan ‘Askari. He went into minor occultation in his prime of life when his four deputies served as intermediaries between him and his followers. After sixty-nine years, he went into the major occultation and he will rise upon Divine Command. This book is a collection of thematically arranged hadiths based on major classical Shi'i hadith sources, such as Bihar al-Anwar and Kamal al-Din. The hadiths which have been collected relate to Imam Mahdi’s birth; prime of life; minor and major occultations; deputies; signs and causes of his rising; and the fruits of his rising in the last days of the world.