AbstractThis study investigates the meaning-form interface in the BalkanSprachbund(BS), by researching five different languages: Italian, Russian,Bulgarian, Romanian, and Greek. I consider two models that account for recurring properties of the relevant languages in theSprachbund: convergence and diglossia. If convergence is the cause behind shared features typical of the BS, that predicts that Bulgarian and Romanian would be more transparent than Russian and Italian. Under the diglossic analysis, Koine Greek is assumed to be the source of shared features, which predicts that the BS languages, Romanian, Bulgarian and Greek, would be similar. To compare the two models, I investigate twenty-four opacity features, divided into five categories: Redundancy (one-to-many), Fusion (many-to-one), Discontinuity (one meaning split in two or more forms), Form-based Form (forms with no semantic counterpart: zero-to-one), and a group of typical BS features. The results are consistent with the diglossia model: Romanian,Bulgarianand Greek manifest similar features, which points in the direction of diglossia as the underlying cause of language similarity.