The Enders Game series -

Chronological order

Earth Unaware
Earth Afire
Earth Awakens (Not out yet)
First Meetings
Ender's Game
Ender's Shadow (Note: The events of Ender's Game and Ender's Shadow take place in roughly the same time period.)
A War of Gifts (Note: This takes place during Ender's Game/Ender's Shadow.)
Shadow of the Hegemon
Shadow Puppets
Shadow of the Giant
Ender in Exile (Note: This takes place during Shadow of the Hegemon and through Shadow of the Giant)
Shadows in Flight
Speaker for the Dead
Xenocide
Children of the Mind
Shadows Alive