Corpus linguistics and computational approaches to language constitute an important trend in today’s linguistics, and Slavic historical linguistics is no exception. This chapter serves as an empirical touchstone for the entire volume. Using parallel Greek and Old Church Slavonic data from the PROIEL/ TOROT treebanks, the first attested state of the phenomena covered in the volume is explored, including their relationship to the Greek sources. The chapter covers accusatives with infinitives (Gavrančić this volume, Tomelleri this volume), absolute constructions (Mihaljević 2017), deverbal nouns (Tomelleri this volume), prepositional phrase connectors (Kisiel & Sobotka this volume), numeral syntax (Słoboda this volume), the ordering of pronominal clitics (Kosek, Čech & Navratilova this volume), tense use in performative declaratives (Dekker this volume) and relative clauses (Sonnenhauser & Eberle this volume; Podtergera 2020). The chapter presents corpus statistics on each of the phenomena, and a brief discussion of the possibility of influence from Greek. The chapters that provide their own studies of Old Church Slavonic data (Fuchsbauer this volume on “mock” articles, Pichkhadze this volume on syntactic blocking and Šimić this volume on negative concord), are not replicated, but brought into the discussion when relevant.