The institutional framework reform for monetary management in Argentina and Uruguay between 1930 and 1935 is approached in a comparative way. Despite differences between the countries’ institutions (for example, Argentina had a Currency Board and Uruguay did not), the cautious handling of monetary policy between 1890 and 1930 was an important element in the international insertion of both. In 1935 Argentina and Uruguay took different paths. Uruguay created an Issuance Department within the Banco de la Republica (a commercial bank with Central Bank functions). Argentina created the Central Bank of the Argentine Republic (BCRA) with a heterodox profile for that time. My general hypothesis is that the ideas of leading economists and the way they entered the political process played a decisive role in these different paths. The ideas of key economists in the reform process will be reviewed.