The final set of social structures which Evans-Pritchard describes is the age-set system, which is ordered differently than the systems in the previous two chapters but which still shows evidence of some of the same repeated principles which underlie Nuer culture. Age-set systems are common across many different Nilotic and East African societies, but Evans-Pritchard points out for his professional anthropology audience that the Nuer form is constituted somewhat differently than other commonly-known age-set systems, particularly in regard to a more generalized status of “manhood” (as opposed to moving through discrete stages of manhood, as is the case in other societies).

The age-set system, while ordered differently from the tribe and clan systems, is nonetheless an important structural element in Nuer society. Structured primarily around men, it is comprised of cohorts of contemporaries, male individuals who are inducted into a particular age-set upon their accession to manhood. This transition is done in a ritual between the ages of 14 and 16, in which a group of boys will be ritually cut with six long, horizontal lines across their foreheads, forming scars that will remain for their whole lives.