The purpose of this article is to re-examine the more important extant manuscripts of Livy 21–25 with special reference to omissions and significant errors, and on this basis to try to establish their interrelationship in stemmatic form. A stemma for Books 26–30 has already been drawn up by Professor S. K. Johnson in O.C.T. vol. iv, but, since the tradition for those five books is slightly different from that of the first half of the third decade, it has seemed worth while to draw up a stemma for Books 21–25 independently. The manuscripts to be considered, and the sigla to be employed, are as follows: