A new penal system was established in Mexico according to the new penal and procedural codes issued in 1929 by President Emilio Portes Gil, using the special powers granted to him by the Mexican congress. These new codes abolish capital punishment and suppress the jury, substituting for the latter a council of experts who shall make the diagnosis of the cases and will advise on the treatment required for the criminals. This article explores the interest in the advancement accomplished by the Mexican criminology by Americans specializing in criminology and sociology. It also looks at the recognition by distinguished sympathizers of these new codes on this new tendency in Mexico.