Rachel Hawkins - Hex Hall (Hex Hall #1) (epub, mobi)

Three years ago, Sophie Mercer discovered that she was a witch. It's gotten her into a few scrapes. Her non-gifted mother has been as supportive as possible, consulting Sophie's estranged father—an elusive European warlock—only when necessary. But when Sophie attracts too much human attention for a prom-night spell gone horribly wrong, it's her dad who decides her punishment: exile to Hex Hall, an isolated reform school for wayward Prodigium, a.k.a. witches, faeries, and shapeshifters.
By the end of her first day among fellow freak-teens, Sophie has quite a scorecard: three powerful enemies who look like supermodels, a futile crush on a gorgeous warlock, a creepy tag-along ghost, and a new roommate who happens to be the most hated person and only vampire student on campus. Worse, Sophie soon learns that a mysterious predator has been attacking students, and her only friend is the number-one suspect.

As a series of blood-curdling mysteries starts to converge, Sophie prepares for the biggest threat of all: an ancient secret society determined to destroy all Prodigium, especially her.