The Newbery Medal-winning dystopian book by Lois Lowry is The Giver.
Published in 1993, the novel follows Jonas, a 12-year-old boy selected to become the Receiver of Memory in a seemingly perfect community. The society has eliminated pain, conflict, color, climate, and many forms of individual choice through a system called Sameness. As Jonas receives memories from the older Giver, he discovers the emotional and moral costs hidden behind that orderly world.
The Giver won the 1994 Newbery Medal, which recognizes distinguished contributions to American children's literature. Its dystopian setting is initially presented as safe and harmonious, so the book's darker nature emerges gradually as Jonas learns what his community has sacrificed for stability.
The novel is the first book in the loosely connected Giver Quartet. It is followed by Gathering Blue, Messenger, and Son, which explains why those titles may appear as tempting alternatives. Number the Stars is also by Lowry and won the 1990 Newbery Medal, but it is a historical novel about the Danish resistance during World War II, not the dystopian book described here.