There are over a thousand families listed here. The names are in their Anglicized form, that is, the most generally representative forms in English. Several categories of names appear, including names of the families covered in Part II, by ethnic group; important variant forms of names found in Part II; and names of families which are direct branches of one of the families dealt with in Part II, as opposed to more distantly related tribal branches. Included in this latter category are blood-related septs of the Scottish clans. (Scottish clan septs can be of two kinds; firstly there are the male-line branches, the identifiable of which are covered here, but then secondly there were those not related in the male line, yet who nonetheless followed the chief of the clan, adhering to him for protection. This reflects Scottish clanship’s slightly different development in this regard, as discussed in Part I.)

Finally, it should be noted that in some cases more than one distinct sept bore the same name in English or Gaelic or both, and when one or more of such families are dealt with while others of the same name are not, confusion may arise. To avoid confusion, those not dealt with are listed here but marked "IVL" (indeterminate, various localities), which generally indicates that these families simply did not fall within the main Gaelic tribal sphere, either because they resided outside the Gaelic area, or else because they did not form a cohesive group with the level of real political significance common to the tribal and clan families listed in Part II, hence their exclusion from further consideration. They are included to show, for instance, that all O’Neills are not necessarily of the great Ulster clan, or O’Neill might be the name of a minor family or of some other clan, or even of a family with no historical or tribal significance. In this way I have cross-referenced family names throughout the Gaelic area, so that accuracy might be maintained.