A number of studies have recently noted that monetary integration in the European Monetary Union (EMU) has been accompanied by increased financial integration. This paper examines the channels through which monetary union increased financial integration, using international panel data on bilateral international commercial bank claims from 1998-2006. I decompose the relative increase in bilateral commercial bank claims among union members following monetary integration into three possible channels: A "borrower effect," as a country's EMU membership may leave its borrowers more creditworthy in the eyes of foreign lenders; a "creditor effect," as membership in a monetary union may increase the attractiveness of a nation's commercial banks as intermediaries, perhaps through increased scale economies enjoyed by commercial banks themselves or through an improved regulatory environment after the advent of monetary union; and a "pairwise effect," as joint membership in a monetary union increases the quality of intermediation between borrowers and creditors when both are in the same union. This pairwise effect could be attributed to mitigated currency risk stemming from monetary integration, but may also indicate that monetary union integration increases borrowing capacity. I decompose the data into a series of difference-in-differences specifications to isolate these three channels and find that the pairwise effect is the primary source of increased financial integration. This result is robust to a number of sensitivity exercises used to address concerns frequently associated with difference-in-differences specifications, such as serial correlation and issues associated with the timing of the intervention.