Is there a second book to The Giver?

Gathering Blue, and the Messenger are "sister" books. Lois Lowry states in her interviews that they are not technically sequels. They have the same theme about the need for human connection, but they are NOT sequels. Having read them myself, there are connections between the pieces, but they are subtle and not terribly obvious. The reader must see them for themselves...

In simple terms, there is no sequel.

- The messenger and Gathering blue are both obviously connected, as both main characters in each book are secondary in the other.

But in the Messenger, the leader of the village is obviously Jonas, if you look at the passages describing 'The little red sled' and other facts.

Gathering Blue and The Giver would take place in the same time frame, but in different villages, while Messenger ties both books together with Kira, Matty, and Jonas all living in Village. Gabe is even mentioned at the start of Messenger.

(You must remember that these stories are the outlook of the future not of the past)

EDIT: "Son" a kind conclusion to the quartet has recently been released and is a more direct sequel to The Giver than the other two books. It is set mostly in the same time frame, and Claire (the main character) is Gabe's birthmother.