Her breakthrough film role was in the coming-of-age film Manny and Lo (1996), in which she played a teenage orphan. She drew wider attention and critical acclaim for The Horse Whisperer (1998), in which she played a girl traumatized after losing a leg in a riding accident. She collaborated again with Allen in Scoop (2006) and Vicky Cristina Barcelona (2008). Other films include the family comedy Home Alone 3 (1997), the drama An American Rhapsody (2001), the Coen brothers' film noir The Man Who Wasn't There (2001), the comedies In Good Company (2004) and The Nanny Diaries (2007), and the historical adaptation The Other Boleyn Girl (2008). In 2008 she released the Tom Waits cover album Anywhere I Lay My Head.

She was born and grew up in New York City, where she began acting professionally at the age of eight. She attended the Lee Strasberg Theater Institute for Young People and made her stage debut in the off-Broadway drama Sophistry (1993), starring with US actor Ethan Hawke. Early films include North (1994), Just Cause (1995), and If Lucy Fell (1996).