By Margaret Peterson Haddix

Born third at a time when having more than two children per family is illegal and subject to seizure and punishment by the Population Police, Luke has spent all of his 12 years in hiding. His parents disobeyed once by having him and are determined not to do anything unlawful again. At first the woods around his family's farm are thick enough to conceal him when he plays and works outdoors, but when the government develops some of that land for housing, his world narrows to just the attic. Gazing through an air vent at new homes, he spies a child's face at a window after the family of four has already left for the day. Is it possible that he is not the only hidden child? Answering this question brings Luke greater danger than he has ever faced before.

I don't know anyone who has read these books who didn't love them.  Here is the list of books in the order they should be read.

Among the Hidden
Among the Impostors
Among the Betrayed
Among the Barons
Among the Brave
Among the Enemy
Among theFree