At the age of 9, she started piano studies at the Milan Conservatory, intending to become a pianist. When she was singing in the Conservatory choir at 12 years old, she was noticed by Giulio Bertola and Bruno Casoni. Under their recommendation, she switched to singing, in alto, which resulted in vocal troubles. She only recovered her voice after studying with Giovanna Canetti, under whose instruction she developed into a soprano.
She made her professional debut in 1990 as Ines in Il trovatore conducted by Zubin Mehta with Luciano Pavarotti as the main role at the Teatro Comunale, Florence. In 1992, she debuted in the US at the Opera Company of Philadelphia as Micaëla in Carmen. She made her Metropolitan Opera debut in 1995 as Micaëla in Carmen and has gone on to sing in over 80 performances there including Donna Elvira in Don Giovanni, Fiordiligi in Così fan tutte, Angelica in Suor Angelica, Desdemona in Otello, the title role in Luisa Miller, Amelia in Simon Boccanegra, Vitellia in La clemenza di Tito, and Alicia Ford in Falstaff.
She performed in two editions of Glyndebourne Festival Opera, in Graham Vick's new productions of Così fan tutte (Fiordiligi, 1998) and Don Giovanni (Donna Anna, 2000). In June 1998, she was featured in the role of Liù in Turandot at the Forbidden City, an outdoor production of the Puccini opera. In December 1999, she sang Alice Ford in Vick's new Falstaff, which opened the first season after Royal Opera House's refurbishment.
In December 2004, she added Elisabetta di Valois in Don Carlo to her repertoire, alternating the role with Adrianne Pieczonka at the Teatro Comunale, Florence.
In December 2008 she starred in a new production of Massenet's Thaïs, inaugurating Teatro Regio di Torino's new season.
In 2012, she debuted in the title role in Adriana Lecouvreur at the Liceu.