How Can a Child Become Emancipated from Her Parents?

IIRC, this depends upon the childs age, his/her parents and the country he/she resides in at the very least. It might stand to reason that the child would have to prove that he/she is capable of looking after his/her self, too.

Seb's right, there are a lot of variables that make this an "it depends" type of answer. Basically, a child would have to prove they are able to take care of themselves (financially and otherwise) better than their parents have thus far. Wikipedia, as usual, has a good write-up on emancipation of minors, which is what this is referred to in the legal system.

A couple child movie stars who filed for legal emancipation are Drew Barrymore and Macaulay Culkin. Generally, they do so because their parents are in the role of their manager and misusing or otherwise abusing that privilege (stealing money, entering into bad contracts, abuse, etc.) Offhand, I'm not aware of any non-child actors who've filed for and won legal emancipation from their parents or other legal guardians, but I'm certain it happens.