This chapter offers a unified account of two (at first blush independent) instances of syntactic change in Latin. Both developments are related to the system of clausal complementation. First, whereas Classical Latin typically uses infinitival clauses (so-called AcIs) to express embedded declaratives, these structures are later replaced by finite clauses, usually introduced by a complementizer. The opposite happens in the case of causatives, where a non-finite (infinitival) strategy is innovated. I propose that the key aspects of these two changes can be reduced to a single, more general, parametric change affecting Latin clause structure, namely the way in which the clausal EPP-requirement is satisfied, a change which affected possible patterns of subject placement (Danckaert 2017). The main mechanism needed to account for the observed facts is reanalysis of the Primary Linguistic Data by the language acquiring child.