Magic or Madness by Justine Larbalestier

Reason Cansino, so named by her mother who wanted her life to be governed by nothing but logic, has grown up constantly moving around the Australian bush.  Her mother ran away from home when she was 12 because, as she tells Reason, her mother is a terrible, evil person who "thinks" she is a witch.  Unfortunately for Reason's mother, the book opens with her being committed to a mental hospital, and Reason being placed in the custody of her grandmother, Esmeralda.

Reason's fear and distrust of her grandmother is surprising to her new neighbor, Tom, who thinks that Esmeralda is the greatest person ever-- and small wonder, because she's been teaching him magic.  But despite their diverging views on Esmeralda, the two teens find common ground when Tom reveals that his mother is in the mental hospital too.  Reason puts her plans to run away on hold while Tom teaches Reason more about her family history and the secrets of her grandmother's house.  Namely, the back door's portal to New York City...

The first in a trilogy, Magic or Madness is a new and unique take on how magic works, while also serving as a backdrop to the many culture clashes that occur in the story.  The title refers to how in this world, something as powerful as magic takes its toll on the human mind-- an amazing idea that almost never gets explored in witchy fiction (yes, we all love karma and the Law of Three, but not all consequences are external!)  I loved the way Larbalestier described Reason's upbringing from her own perspective-- as if there was nothing unusual about moving around every few months, not always knowing where you are going or where your next meal is coming from.  Likewise, she presents very nuanced points of view between the different "factions" of characters: New Yorkers vs. Aussies, the pro-magic Tom and Jay-Tee vs. the anti-magic Reason-- even touching upon the subtle and not-so-subtle racism the half-Aborigine Reason faces in both countries.

This is the first book I've read (that I can remember) that presents magic as more of a problem than a power, and by the end you'll hope that they can find a way to get rid of their powers without losing their minds.  I have every intention of reading the rest of this trilogy and strongly recommend it!

If you're not convinced you can read the first two chapters on Larbalestier's website!