I'm frequently asked what book on evolution should be the next one read by a person with a knowledge level on the subject of (fill in the blank). This page is an attempt to answer that question. Because I have not read all the books listed below, (and it has been several years since I read some of them so my memory is hazy) a few may be mischaracterized. Hopefully, none are off by more than one level. If you feel a book listed below is included in the wrong section, please explain why in an email to me, and I may move it. Thanks.

Beginner (Virtually no knowledge of the subject matter)

The Beak of the Finch by Jonathan Weiner (Highest recommendation)

Charles Darwin and the Theory of Natural Selection by Renee Skelton

Darwin For Beginners by Jonathan Miller & Borin Van Loon

Evolution by Linda Gamlin
Evolution and the Myth of Creationism by Tim Berra
The Evolution Book by Sara Stein

Great Feuds in Science by Hal Hellman (only a small portion of this book deals with evolution)

Lucy's Legacy: Sex and Intelligence in Human Evolution by Alison Jolly (portions of this book may fall under "Advanced Beginner")

Next of Kin: What Chimpanzees Tell Us about Who We Are by Roger Fouts

Patterns in Evolution : The New Molecular View by Roger Lewin (portions would fall under Advanced Beginner)

Science and Earth History: The Evolution/Creation Controversy by Arthur N. Strahler (make it through this one book and you will become Intermediate)
Shadows of Forgotten Ancestors by Carl Sagan

The Tree of Life: The Wonders of Evolution by Ellen Jackson

Why People Believe Weird Things by Michael Shermer (only a portion deals with evolution)

Advanced Beginner (Some knowledge of the subject but it has been a while)

The Blind Watchmaker by Richard Dawkins (portions may fall under Intermediate)
Bonobo: The Forgotten Ape by Frans de Waal
Brain Waves Through Time by Robert T. DeMoss

Children of Prometheus by Christopher Wills
Civilization and the Limpet by Martin Wells

Darwin by Adrian Desmond & James Moore
Darwin and Design: Does Evolution Have a Purpose? by Michael Ruse
Darwin's Dreampond by Tijs Goldschmidt (portions would fit in Beginner and portions would fit in Intermediate--overall this is an outstanding source)
Dinosaur in a Haystack by Stephen Jay Gould

Huxley: From Devil's Disciple to Evolution's High Priest by Adrian Desmond

Life: A Natural History of the First Four Billion Years of Life on Earth by Richard Fortey

The Origin of Species by Charles Darwin
Origins Reconsidered by Richard Leakey

Promiscuity: An Evolutionary History of Sperm Competition by Tim Birkhead (portions would fit in Intermediate)

Systematics and the Origin of Species from the Viewpoint of a Zoologist by Ernst Mayr (portions fall under all the other levels too--perhaps the best introduction to taxonomy from an evolutionary perspective that you will find)

Tree of Origin: What Primate Behavior Can Tell Us about Human Social Evolution Edited by Frans deWaal

Unweaving the Rainbow by Richard Dawkins (only a portion of this book deals with evolution)

Intermediate (Fluent in basic Darwinian selection and decent grasp of the history of life)

Children of the Ice Age by Steven M. Stanley

Darwin's Dangerous Idea by Daniel C. Dennett

Evolution: A Theory In Crisis by Michael Denton (A good example of what happens when religion clouds an author's view. Denton has since reversed his denial of macro-evolution which he tries so hard to prove didn't and doesn't occur in this book.)

On Fertile Ground: A Natural History of Human Reproduction by Peter T. Ellison
Full House by Stephen Jay Gould

The Meme Machine by Susan Blackmore
The Moral Animal: Evolutionary Psychology and Everyday Life by Robert Wright

The Pony Fish's Glow : And Other Clues to Plan and Purpose in Nature by George Williams

Science As a Way of Knowing: The Foundations of Modern Biology by John A. Moore
Sociobiology: The New Synthesis by E. O. Wilson (parts may be considered Advanced)

The Triple Helix: Gene, Organism, and Environment by Richard Lewontin

Why We Feel: The Science of Human Emotions by Victor S. Johnson

Advanced (You are planning on getting a college degree in a related subject)

The Adequacy of the Fossil Record Edited by Stephen K. Donovan & Christopher R. C. Paul (Very Advanced and specialized)

Cells, Embryos, and Evolution by John Gerhart & Marc Kirschner (although mostly Advanced to Very Advanced, it will serve as an excellent reference for Intermediate readers)

Evolution by Mark Ridley (This is Advanced more for its range of content and depth on issues most people interested in evolution have never heard of more than anything else. Intermediate and Advanced Beginners will want to use it as a reference.)

Lamarck's Signature by E. J. Steele, Robyn A. Lindley, & Robert V. Blanden (Portions would fall under Intermediate. Chapter 7 would fall under Silly.)

Phylogeography: The History and Formation of Species by John C. Avise