Current (to the best of my knowledge) as of August 18 2015.
January: The Boys in the Boat by Daniel James Brown
February: When We Were Orphans by Kazuo Ishiguro
March: Shadow of the Wind by Carlos Muiz
April: The Spies of Warsaw by Alan Furst
May: Why Does the World Exist by Jim Holt
June: Just food and voting. No book discussion.
September: Goldfinch by Donna Tartt and A Moveable Feast by Ernest Hemingway
October: The Great Bridge: The Epic Story of Building the Brooklyn Bridge by David McCullough
November: Being Wrong by Kathryn Schulz
December: Hotel Florida: Truth, Love, and Death in the Spanish Civil War by Amanda Vaill