A review of the literature pertaining to identification criteria for firearms and toolmark identification was performed. Thirty-four articles were reviewed including empirical studies of consecutively manufactured barrels, firing pins, breechfaces, and assorted tools. Also reviewed were mathematical and computer models developed for the purpose of developing a standard identification criteria. These articles are reviewed in a format to allow interested parties to learn what has been done in the field so as to permit a better articulation of their own criteria for identification.