[2] In 1954 she made her Broadway debut as a member of the chorus in the world premiere of Gian Carlo Menotti's The Saint of Bleecker Street.
[2] In 1962 Roberto sang with George Shirley on The Bell Telephone Hour and appeared as Violetta in La traviata with conductor Boris Goldovsky and the New England Opera Theater.
[6] In 1965/1966 Roberto toured the United States with the Metropolitan Opera National Company performing the roles of Cio-Cio-San in Giacomo Puccini's Madama Butterfly and Frasquita in Carmen.
[9] That same year she made her debut at the Seattle Opera as Nedda in Pagliacci with Roald Reitan as Silvio and James McCracken as Canio.
[12] That same year she made her debut at the New York City Opera as Mimi in La bohème with Plácido Domingo as Rodolfo.