Thomas was commissioned to record the music for the 1997 Ringling Bros. and Barnum & Bailey Circus tour through the Americas, and performed live on selected dates.

[26][27] In early 1998, Thomas moved to Los Angeles, California, to begin recording Mi Día de la Independencia, alongside her producers Carlos Lara and Max di Carlo, it was finished recording in late 1998; the album was released around the world in early 1999, as Thomas turned 18.

[32] Subsequently, in early 2000, the musician released officially the acoustic ballad "Ahí Estaré" (I'll Be There); first, the studio version won significant airplay on the radio in 1999.

[33] She also worked for the TV ad campaign of Sabritas snacks company, with an adaptation of her successful single "Corazón Perdido".

[40][41] Before the official release of Polen, on Sunday, February 25, 2001, Thomas performed 3 songs at Festival de Viña Del Mar held in Chile.

[44][45] Meanwhile, Thomas hosted alongside Colombian rock-singer Juanes in the first original edition of the Nickelodeon Kids' Choice Awards Latin America, held in Santa Monica, California, in 2001.

[47][48] On April 11 and 23, 2002 the studio album Polen was remastered and re-released only in the United States to increase the popularity of the album; it coincided with the American Nickelodeon Kids' Choice Awards show hosted by Thomas for the IberoAmerican broadcasting, in which she conducted interviews with several actors and music groups of that time including Jennifer Love Hewitt, Mike Myers, Dana Carvey, O-Town, No Secrets, Antonio Banderas, Melanie Griffith or Ashley Judd among others.

[49] She also released the last official single in her career, "Para Ti" (It's For You), a semi-acoustic track which reached Top ten in some countries.