The Moorchild (Newbery Honor Book)

Brought up as one of the Moorfolk--small beings who live in a cavern beneath the moor--young Moql finds her life abruptly changed when the Folk discover she cannot make herself invisible to humans. The Folk cast her out, exchanging her for a human baby they can raise as a servant, and Moql becomes Saaski, a changling child. Struggling to fit into village life, Saaski's final comprehension of who she is and what she must do make a mooving story with contemporary parallels.