Having clarified the basic concepts related to age class systems, we need to take an objective overview of the ethnographic situation before any further discussion. This is no easy matter. We must somehow establish an adequate method for using the extremely uneven documentary material relevant to the question. The reports by the first ethnographers, describing rituals and activities they had actually seen, are certainly most valuable, but they are often the least satisfactory since the observations are often lacking in detail or not to the point. In contrast, more recent reports, normally undertaken by professional scholars, do not always refer to firsthand data and frequently are inconsistent in their use of concepts and terms regarding age class systems.

To overcome such difficulties, it may be useful to devise a typology that permits us to distinguish among the systems on the basis of certain specific characteristics and to examine the resulting varieties comparatively. In analyzing the basic concepts, I have already identified some of the structural principles that underlie the working of age class systems. I have also pointed out the dynamic relationship that exists between classes and grades forming the basic structure of the system and the mechanism for the distribution of power. The structure and functions of age class systems can thus be employed as our first two criteria for the choice of ethnographic models. These must be based on aspects that are distinguishing features of the main systems.