Late eighteenth or early nineteenth century.
In the run-down mansion of Don Magnifico, Baron of Montefiascone, his two daughters, Clorinda and Tisbe, try on finery while Cenerentola (Cinderella), his stepdaughter, whose given name is Angelina and who serves as the family maid, sings a forlorn ditty about a king who found a wife among the common folk.
When a beggar appears, the stepsisters want to send him away, but Cenerentola offers him bread and coffee. While he stands by the door, several courtiers arrive to announce that Prince Ramiro will soon pay a visit: he is looking for the most beautiful girl in the land to be his bride. The sisters order Cenerentola to fetch them more jewels. Magnifico, awakened by the commotion, comes to investigate, scolding the girls for interrupting his dream of a donkey that sprouted wings. When he learns of the prince's visit, he exhorts the girls to save the family fortunes by capturing the young man's fancy.
All retire to their rooms, and Prince Ramiro - disguised as his own valet - arrives alone, so as to see the women of the household without their knowing who he is. Cenerentola is startled by the handsome stranger, and each admires the other. Asked who she is, Cenerentola gives a flustered explanation about her mother's death and her own servile position, then excuses herself to respond to her stepsisters' call. When Magnifico enters, Ramiro says the prince will be along shortly.
Magnifico fetches Clorinda and Tisbe, and they greet Dandini - the prince's valet, disguised as the prince himself - playing his role to the hilt as he searches for the fairest in the realm. The sisters fawn over Dandini, who invites them to a ball.
Don Magnifico also prepares to leave, arguing with Cenerentola, who does not want to be left behind. Ramiro notes how badly Cenerentola is treated. His tutor, Alidoro, still dressed as the beggar who came earlier, reads from a census list and asks for the third daughter of the household. Magnifico denies she is still alive.
Once Dandini has left with Magnifico, Alidoro tells Cenerentola she is to accompany him to the ball. Casting off his rags, he identifies himself as a member of the court and assures the girl that heaven will reward her purity of heart.
Dandini, still posing as the prince, escorts the two sisters into the royal country house and offers Magnifico a tour of the wine cellar, hoping to get him drunk. Dandini disentangles himself from the sisters and says he will see them later.
In a drawing room of the palace.
Magnifico is hailed as the prince's new wine counselor. No one, he decrees, shall mix a drop of water with any wine for the next fifteen years. Looking forward to the feast, he and his attendants leave. Dandini reports to the prince with his negative opinion of the two sisters. This confuses Ramiro, who has heard Alidoro speak well of one of Magnifico's daughters.