This is the biography of the Zaydi Imam, 'Abdullah b. I:Iamzah, who stood against the Ayyfibid's rule in Yemen, of his time. The biography covers the Imam's life, family background and relations with other sects. These include the Shi'ah and the Zaydis, particularly those of the Mutarrafis. The biography also gives a detailed picture of the Imam's relations and conflicts with the local Ayyfibids in Yemen. As the author considered the Imam a great authority in the field of religion and thinking, we find a large amount of quotations from the Imam's works, both poetry and prose. The author, as the Imam did, gave special attention to the authority of the Fatimi 'Alawid's descendants in the field of religion, and in particular how the post of Imamate should be aquired only by them. The importance of this work comes from the fact that it is the only surviving complete biography of this Imam, written by one of his well known and distinguished contemporaries. The highly classical Arabic which the author used to write the biography, increased the prestige of the work, and added importance to it. This reflects AI-Mu1;lalli's authority in the fields of Arabic language, literature and history. The thesis consists of two main parts; Section A (or 1) is a short introduction and study to the text and its author, followed by the English translation of the Arabic text, while Section B (or 2) is the edited Arabic text (the biography). Finally the conclusion, will illustrate the main points in the whole work. I hope the work I produce can represent a valuable addition to Yemeni history, literature and beliefs.