Norma is an Italian opera in two acts by Vincenzo Bellini , first performed at La Scala in Milan , on December 26 , 1831 , libretto by Felice Romani , after Louis Alexandre Soumet 's play Norma ou l'infanticide . Norma is a tragedia lirica or opera in two acts by Vincenzo Bellini with libretto by Felice Romani after Norma , ossia L'infanticidio ( Norma , or The Infanticide ) by Alexandre Soumet . First produced at La Scala on December 26 , 1831 , it is generally regarded as an example of the supreme height of the bel canto tradition .