Un giorno di regno, ossia Il finto Stanislao (A One-Day Reign, or The Pretend Stanislaus, but often translated into English as King for a Day) is an operatic melodramma giocoso in two acts by Giuseppe Verdi to an Italian libretto written in 1818 by Felice Romani. Originally written for the Bohemian composer Adalbert Gyrowetz the libretto was based on the play Le faux Stanislas written by the Frenchman Alexandre Vincent Pineu-Duval in 1808. Un giorno was given its premiere performance at the Teatro alla Scala, Milan on 5 September 1840.

Original Name Un giorno di regno, ossia il finto Stanislao
Librettist Felice Romani (based on Alexandre-Vincent Pineux-Duval's play, Le faux Stanislas)
Date of composition 1840
Premiered 1840, September 5th (Teatro alla Scala) in Milan, Metropolitan City of Milan, Italy
First published 1840
Type Opera
Spoken language Italian
Instruments Orchestra
Chorus/Choir
Voice (Baritone) - Cavaliere di Belfiore, a French officer impersonating Stanislao of Poland
Voice (Bass) - Barone di Kelbar, the usurper
Voice (Soprano) - The Marchesa del Poggio, a young widow, the Baron's niece, in love with Belfiore
Voice (Mezzo-Soprano) - Giulietta di Kelbar, the Baron's daughter
Voice (Tenor) - Edoardo di Sanval, a young official, la Rocca's nephew
Voice (Bass) - La Rocca, Treasurer to the Estates of Brittany
Voice (Tenor) - Count Ivrea, Commandant of Brest, engaged to the Marchesa
Voice (Bass) - Delmonte, esquire to the false Stanislao
Autotranslations beta Giuseppe Verdi: A One-Day Reign, or The Pretend Stanislaus "Melodramma giocoso in due atti"
Giuseppe Verdi: A One-Day Reign, or The Pretend Stanislaus "Melodramma giocoso in due atti"
Giuseppe Verdi: A One-Day Reign, or The Pretend Stanislaus "Melodramma giocoso in due atti"