Instead of a Factor Four (1995), by Amory Lovins, Hunter Lovins, and Ernst von Weizsäcker, I believe Amory's book called "Brittle Power" has more relevance relating to our global environmental and political situation. The others seem 'right', especially Seuss' The Lorax. - Scott Sklar

I would have included A Sand County Almanac and Essays on Conservation by Aldo Leopold.

Far ahead of his time when he wrote it about 1950 I believe. I first read it in 1970 and it made a tremendous difference in my life.

He made the point that no National Park in and of itself was large enough, when most people were thrilled to create small local wayside places.

It's not waste unless we waste it.

I cannot speak for other Americans, but a few "wildlife and wilderness classics" would definitely be on my list.  I entirely agree with Norm Ruttan's suggestion, for example.  In fact it surprised me that Aldo Leopold had not originally been included.  Perhaps because books of that sort are so often about experiences in North America, they do not appeal to British readers.  Two more recent authors whom I am fond of are Peter Matthiessen (e.g. "The Snow Leopard," "Sand Rivers") and Barry Lopez (e.g. "Of Wolves and Men," "Arctic Dreams").

I have no idea what the category "overt spirituality" might include.  Brian Swimme's "The Universe Story"?  Thomas Berry's "The Dream of the Earth"?  Those authors have indeed inspired many people.

C.S.Lewis's fiction might possibly count as environmentalist: in the Perelandra trilogy explicitly, but also in the Narnia Chronicles, his Christian world view includes an idyllic affection for the natural world, with which humans live in harmony; over against that, ugly industry is associated with the Devil.  There is something of that in J.R.R.Tolkien's Lord of the Rings too, especially the description of Saruman's horrifying orc-factory at Orthanc, involving the bit-by-bit destruction of the forest of the Ents.

You can hardly get more British than that!

Gerald Durrell's "My Family and Other Animals" I have not read, but it was recently made into a TV special, perhaps as one of the offerings of Masterpiece Theatre, and shown on PBS earlier this year.  It was very charming and pretty, but I did not like the fact that the animal-loving boy was not content to observe animals in the field; rather, he had to collect them and keep them in the house.

Chickens are our cousins! So are other sensitive animals! Enough is enough! No more factory farms!

I too was looking for "A Sand County Almanac" to be on the list.  Some other early naturalists would be Prost, Thoreau (and Emerson), Whitman, etc.  Perhaps on the more recent list I would definitely put Edward Abbey, Wendell Berry, and "Wilderness and the American Mind" by Roderick Nash which is a great, thought-provoking work.  On the kids side you can't have the Lorax and leave out Shel Silverstein's "The Giving Tree", crazy brits!

This book, by William McDonough and his business partner describes the philosophy of working with nature, where what we do improves the environment - as nature herself does. They describe several projects where the authors created sustainable, health-giving industrial processes.

And the book itself was made of some new material that was designed to be 'upcycled,' meaning it could be remade into something something of similar or higher quality than a book - not a park bench. McDonough and his partner are leading by example.

I second the nomination of Cradle to Cradle. While some books raise awareness through sheer poecy (Walden), and others alert the public of impending doom (Gaia), this one provides a comprehensive framework for action. From ideas for repackaging toothpastes (why the box around the tube?) to upcycled products, the book centers on creating internal feedback cycles---a.k.a. cradle to cradle production. For me, at least, the result was a feeling of empowerment and excitement. We will always need the clarion calls of Silent Spring and the whistle-blows of Crimes Against Nature, but the optimistic "how to" of Cradle to Cradle lands it in my personal top ten.

A couple of books from Bill Peet with strong environmental themes that I enjoyed when I was a kid (and still do):

Farewell to Shady Glade
The Wump World

Both focus on the impact of outside forces on the native inhabitants of an eco-system. I was a big fan of pretty much all of his books, but these two really stand out in my memory these days.