The Fatimid assertion to the universal caliphate was predicated on their claim to be sole designated successors of the Prophet Muhammad. This descent made them part of a larger and distinct social group, the ashr?f, the recognised descendants of the Prophet Muhammad. Whereas the veracity of the Fatimid genealogical claim has arguably been over played in the sources resulting from anti-Ismaili polemic, and perhaps therefore over emphasised in contemporary scholarship, the interactions of the Fatimids with the various segments of the ashr?f in North Africa as well as in Egypt has remained relatively under examined. This paper seeks to address this lacuna. A close reading of the sources reveals that the Fatimids had a ubiquitous yet intricate relationship with the ashr?f. This ranged from close co-operation to that of outright hostility. On the one hand, the ashr?f were depicted as being among the most outspoken opponents of the Fatimid claim of their genealogical descent from the Prophet. This is evident by the well-known anecdote of Shar?f al-?ab??ab?‘? supposed questioning of the Fatimid Imam-caliph al-Mu‘?zz’s ancestry upon his arrival in Egypt in 973 CE. The pivotal role of the ashr?f in rejecting the authenticity of Fatimid descent was exemplified by their signing of the so-called ‘Baghdad Manifesto’ in 1011CE. Equally, the sources also reveal instances of conciliation and cooperation between the Fatimids and the ashr?f. These include Fatimid mediations to resolve blood-feuds among the various ashr?f clans who held leadership positions in the Hijaz in the 10th century, and their special pardon and exclusive privileging of the Idr?sid rebels in the Maghrib. Similarly, the ashr?f also utilised their kinship links with the Fatimids to negotiate favourable treatment, as is evident from the Egyptian delegation that met with Fatimid Commander Jawhar upon his arrival in Egypt in 969 CE. In studying these interactions, the paper aims to develop a rounded understanding of how and to what end were the kinship ties between these two socially important groups calibrated.