Matter of fact, the life of Sheikh Issa bin Salih Al-Harthi is a continuation of the historical and cultural role played by his family which started with his grandfather Sheikh Rashid bin Said bin Rajab – the author of Bin Rajab Manuscript and one of the leading judges of Imam Sultan bin Saif Al-Yarubi. His father is Sheikh Salih bin Ali Al-Harthi who enjoyed a prominent political status in Oman as a political and tribal leader besides his well-established intellectual and religious stature. This study aims to shed light on the life of Sheikh Issa bin Salih Al-Harthi and his political, social and culturalrole in Oman. The introductory chapter presents a vivid picture of the dominant political situation in Oman during the late era of Sheikh Salih bin Ali Al-Harthi until his death in 1896 while chapter one highlights the upbringing of Sheikh Issa bin Salih Al-Harthi, his personality, his attitudes toward certain social issues and the intellectual dimension in his life. The researcher attempts to compile a roundup and integrated study about the biography of Sheikh Issa Al-Harthi and to depart from the general framework of the previous historical studies which were successful in addressing the political aspect of his life without touching on other aspects. However, this study reveals that the social and intellectual aspects are no less important and here come the importance of this study and the fresh addition it features. Chapterstwo and three of the study reveals the political role played by Sheikh Issa Al-Harthi in shaping the historical and political events in Oman well throughout the first half of the twentieth century until his death in March 1946. The study meticulously narrates his interconnections with Imam Salim bin Rashid AlKharousi and Imam Mohamed bin Abdullah Al-Khalili, his relationships with Sultan Faisal bin Turki, Sultan Timor bin Faisal and Sultan Said bin Timor as well as his role and political opinions in light of the relationship between the Imamah and the Sultanate, specially the signing of Al-Seeb Treaty in 1920 that succeeded in halting the war and establishing peace in Oman.