In this paper, we provide new evidence for the hypothesis that in some languages, differential object marking (DOM) may have evolved from marking of the information structural category of topicality. While Iemmolo (2010) suggested that topic left-dislocation might have facilitated the evolution of DOM, and Dalrymple and Nikolaeva (2011) argued for systematic marking of secondary topics as the source of DOM, we suggest a third possible grammaticalization source within the topical domain: the prepositional marking of embedded topics. In particular, we show that the Romanian DO (Direct Object) marker pe had a function as marker of embedded topics in Old Romanian. Moreover, we show how DOM in Old Romanian may additionally have been facilitated by the re-analysis of embedded topics as themes in certain constructions.
