"There are a few different theories as to the origins of the Frango name. One theory is originated by the combination of "Fr" from Frederick’s and the "ango" from the word tango. Employees trained at Frederick and Nelson were taught that the name was an acronym for FRederick And Nelson COmpany. The C was changed to a G since Franco suggested a different meaning. Some have also said that Frango is a portmanteau for FRederick And Nelson GOodness.
A much-repeated theory—repeated, at times even by people very close to the stores concerned—states that Frederick & Nelson originally called the chocolates Franco Mints. In the 1930s, after Frederick & Nelson's was acquired by Marshall Field's, the name was changed to Frango mints after the Spanish Civil War, when Generalísimo Franco met with Hitler, to avoid similarities to the Spanish dictator's name. However, the brand name Frango was trademarked June 1, 1918.