Caliphate in Islam, refers to leadership of the Muslim ummah in successorship of Prophet Muhammad. The history of caliphate in this sense spans over centuries and has all along been understood as political leadership in succession to the religious leadership of the Prophetic model. The Ottoman caliphate owed its authority to its claimed lineage back to the Caliphate established after the death of Prophet Muhammad. Linked to the sultanate that ruled the Ottoman empire, it established a particular model of rulership that bridged the political and religious realms. The proclaimed ISIS caliphate, that lasted for only three years, has been subject to intense media and political scrutiny. It was an attempt to re-establish a caliphate on the post-Prophetic model in the heartlands of the Muslim world. To establish itself, its leader has asserted the right to militant jihad over Muslim populations in the area and against outside interference from the non-Muslim powers. Both these caliphates demonstrate different models for authority and the relationship between religion and power in the Muslim world. The lesser known but surviving Ahmadiyya Caliphate founded in 1908 in the small town of Qadian in India, has spread across the globe, including significant populations of Muslims in the West. This model of caliphate was around in the years when the Ottoman caliphate was collapsing and was functional in the years that saw the rise and fall of the ISIS caliphate; Both the Ottoman and the ISIS caliphates have disappeared, but the Ahmadiyya caliphate still survives. This comparative book is an attempt to see what the Ahmadiyya caliphs have been doing for the last 110 years--holding the same banner but propagating a different type of Islam and asserting a very different model of power and authority. This work starts off by understanding the concept of caliphate in light of the Islamic canonical and classical works (Quran, Hadith and classical Islamic literature) going on to see how the concept evolved in the centuries after Muhammad and his first four caliphs (the Rashidun). Having seen the Islamic concept of caliphate and how it was practiced (along with all the deviations that it went through), this work will focus on seeing the foundational grounds of Ahmadiyya caliphate and how it contested with the centuries-old Ottoman caliphate in its final years and how it outlived the Ottoman caliphate. Having remained functional for over a century, it was to contest another caliphate--the ISIS caliphate--and yet to outlive it too.