The distinctive characteristic of the generational model is its recruitment principle, defined by the structural distance between father and son fixed in terms of age grades. Thus, for example, among the Oromo the rule dictates that the individual be placed in the age class of the gada system at a distance of five grades or forty years, from the grade occupied, at the moment, by the father.

The generational principle is fundamental and underlies the structural order of this model. As a result, postpubertal initiation, which in the initiation model is the determining factor in marking individual autonomy as well as in establishing the structure of the model, is not central. In the societies that reflect this model, a boy can enter the system in infancy, provided the rule of the structural distance from his father is respected. Moreoever, certain rites, normally tied to postpubertal initiation, as, for example, circumcision, are not rendered essential; if they are carried out, they are performed at times and in ways that seem incongruous because they appear to be removed from the normal concept of postpubertal initiation.

It is worth stressing, also, that the term generation, with reference to the generational model, does not necessarily mean that the class is the aggregation of fathers or of sons; rather, it emphasizes the structural distance by which the position of a son within the age class system is defined by the position of his father in the same system.