age grade and age set, differentiation of social role based on age, commonly found in small-scale societies of North America and East Africa. Age sets are a type of sodality (nonresidential groups that cut across kinship ties and thus promote broader social solidarity) of young men who usually cooperate in secret ritual or craft performances together; individuals generally remain closely associated with their age set throughout their life. They are initiated into maturity and pass through age grades, the more general term denoting recognized stages of maturation that entail distinct rights and duties. Age grades may be marked by changes in biological state, such as puberty, or by socially recognized status changes such as marriage and the birth of a child. Persons of junior grade may defer to those of more senior grade who in turn teach, test, or lead their juniors. The Masai have an age-graded society.