Kissing Shakespeare by Pamela Mingle (Delacorte hardcover, 14 August 2012).
Miranda's parents are acclaimed Shakespearean actors. And that's what Miranda wants to do when she finishes school, at least until she screws up her performance of Kate in her school's production of The Taming of the Shrew. She's backstage after the show, still agonizing about it when she's approached by fellow cast-member Stephen Langford.
Miranda hardly knows Stephen, who appeared at the school just in time to audition for Shrew. He didn't hang out with the other students, and never revealed much about himself.
When he asks her if she'd like to meet William Shakespeare. Miranda assumes he wants her to go to a Renaissance Faire or some kind of re-enactment with him, and ungraciously declines.
He explains that he's a contemporary of Shakespeare's, and that the aspiring playwright is being wooed by the Jesuits for the priesthood, which is very dangerous in Elizabethan times, as Catholics (particularly Jesuits) are being put to death by fanatical Puritans. If Shakespeare becomes a priest, none of his amazing work will be created, and all of history will be changed.
Miranda doesn't believe him, and after some discussion, he finally tosses her over his shoulder and carries her up to the roof of the building. There, he pulls out an astrolabe which he uses to open a portal into the sixteenth century.
Even when Miranda suddenly finds herself lying on the ground in a forest, she's skeptical. When she runs away from him, intending to find help, she comes across a pair of men who seem confused by her attire and strange manner of speech. She realizes that, indeed, she has been transported to Shakespearean times, and that Stephen intends her to seduce the young William Shakespeare in order to keep him from joining the priesthood. Meanwhile, she has to learn how to fit in as a teenaged girl in sixteenth century England.
Time travel is a concept that makes less sense the more one thinks about it. Mingle's book is no exception, but it is well-written and -researched, and will appeal to fans of the sub-genre.
*FTC Full Disclosure: I picked up an ARC of this book at the ALA convention in June 2012.