A hall in the Baron’s castle. Don Magnifico, Baron of Montefiascone, lives in his castle with his spoilt and pampered daughters, Clorinda and Tisbe, and his stepdaughter Angelina (called Cenerentola), who is forced instead to do the humblest housework . Angelina consoles herself by singing a song about a prince who sets out to find a bride, finds three aspirants and eventually chooses the kindest and most innocent. A beggar knocks at the door. Clorinda and Tisbe turn him away rudely, but Angelina takes pity and gives him something to eat. A party of knights arrive, bearing an invitation to Don Magnifico and his daughters from the prince, who is giving a ball at which he intends to choose the fairest maiden to be his bride. Clorinda and Tisbe frantically set about the task of making themselves beautiful. Their shrill chatter wakes Don Magnifico, who gets up in a bad mood and recounts the strange dream he was having and which must surely be an omen of good fortune. When his daughters tell him of the invitation to the ball, Don Magnifico is certain that all this bears out his dream. The prince, Don Ramiro, now enters. He is disguised as his own valet, as suggested by his tutor, the philosopher Alidoro, who has already carried out an inspection of Don Magnifico’s palace while pretending to be a beggar. The prince finds Angelina alone, and they fall in love at first sight. When he enquires about her identity, the girl is confused and gives evasive answers. The knights now introduce Dandini, the prince’s valet, who by his master’s orders is wearing the prince’s clothes. The prince wishes to remain incognito so that he can watch his aspiring brides in order to guess their intentions. Don Magnifico, Tisbe and Clorinda pay homage to Dandini, whom they believe to be the real prince. Angelina asks permission to go with her stepsisters to the palace; but Don Magnifico tells her to keep quiet, explaining to those present that the girl is only their servant. Observing this scene, Ramiro can hardly contain his indignation. Alidoro, left alone with Angelina, consoles and soothes her and assures her that he personally will accompany her to the ball. Dandini flatters Don Magnifico’s amour proper by appointing him Master of the Royal Cellars. Meanwhile Clorinda and Tisbe do their utmost to charm the prince, but succeed only in displaying their vanity and arrogance. Festive sounds announce the arrival at the palace of an eminent guest. A superbly elegant, veiled lady makes her entry and greatly impresses the court. She takes off the veil to reveal the face of a lovely maiden. She is Angelina, whom Alidoro has escorted to the ball, and although the likeness is noticed, nobody actually recognizes her. Don Magnifico, Tisbe and Clorinda are disturbed by the unexpected appearance of the beautiful guest, who could seriously jeopardize their ambitions. Don Magnifico’s conscience is uneasy, for he has squandered Angelina’s inheritance to keep his two daughters in luxury and idleness. Now he is anxious to marry one of the two to the prince and so replenish his dwindling resources. Already he pictures himself established at court and besieged by supplicants. Don Ramiro, who also is struck by the resemblance of the lovely unknown maiden to the girl he believes to be Don Magnifico’s servant, overhears a conversation between Dandini and Angelina. The girl has just declined the bogus prince’s proposal of marriage, declaring that she is in love with his valet. The prince is overjoyed at this news and steps forward to reveal his identity and ask for her hand. Angelina gives him a bracelet, and before departing, poses one condition: that she shall be his if he can find her again and if he will accept her true identity. Don Ramiro picks up his disguise and leaves at once, exultant, to search for his beloved. Don Magnifico now approaches Dandini, who continues the pretense and makes fun of him. As the truth slowly dawns on the furious Don Magnifico, he sees all his hopes dashed. Having returned from the ball, Cenerentola is back by the fireside and dreaming of the prince. Her musings are interrupted by the entry of Don Magnifico and the stepsisters, who vent their wrath on her. In the meantime a storm breaks, due to which Don Ramiro’s carriage overturns right in front of Don Magnifico’s house. When the prince enters to seek shelter from the rain, Don Magnifico renews his efforts to ingratiate his daughters with him, while trying to pass off Angelina as their servant. But the prince recognizes the bracelet on Angelina’s wrist, which matches the one received from her as a gift. To everyone’s astonishment, he asks her to recognize him and indicates that she shall be his bride. Alidoro advises the stepsisters to resign themselves, telling Clorinda to look for a husband elsewhere and Tisbe to beg forgiveness from Cenerentola. The court pays homage to the new princess, and Angelina asks her husband to pardon her family. Kindness comes so naturally to her that she is even prepared to forget the injustice suffered at their hands.