Clan MacLean associations traditionally admit those whose spouse, parent, grandparent or great-grandparent bore either the name MacLean or one of the other recognized spellings or septs.

A sept is a family or a kindred (a group of related persons) that for any number of reasons has associated itself with a larger family or kindred. Septs were often small in size and obtaining the protection of a larger more powerful family was of great importance in the unruly Middle Ages and even up to and including the 1700s. In exchange for their protection, the larger family or kindred demanded and received loyalty and sometimes fealty and they treated the sept as part of the overall kindred.