The first part of the supplement to CIL IX is a a critical edition and pictorial documentation of more than 550 newly found Latin inscriptions of the Regio Italiae quarta (territory of the Samnites and Frentani). It includes detailed addenda and corrigenda to about 850 inscriptions already known in the 19th century and edited in 1883 by Theodor Mommsen in CIL IX. With the four subsequent fascicles Supplementum pars I will contain the complete critical modern edition of the Latin inscriptions of the Roman Regio Quarta, the fruit of three decades of research by Marco Buonocore. The second installment of the supplement to volume CIL IX edited by Marco Buonocore includes - for the first time with photos - complete addenda and corrigenda for the inscriptions edited by Theodor Mommsen in 1883. The book documents about 670 newly discovered Latin inscriptions from the Regio Italiae quarta (Marrucini, Paeligni, Vestini) edited according to modern conventions, and includes a general map as well as a short index.