Oscan secondary verbs form their perfect with a suffix -tt-, whose origin has been much debated. After a critical review of earlier suggestions, which have assumed either a reanalysis within a specific model paradigm or some periphrastic source, a new periphrastic theory is presented. According to this proposal, the perfect in -tt-is to be traced back to the past perfective variant of a progressive periphrasis involving a present participle + auxiliary STAND (for BE). Such a combination not only provides a phonologically satisfactory starting point for the attested Oscan forms, but it also enjoys typological support from comparable progressive periphrases both in the Sabellic (OscoUmbrian) subgroup of Italic and in the closely related history of Latin/Romance.