The second book of Kim Stanley Robinson's Mars trilogy, it covers the time between Red Mars and Blue Mars. It's a bit more romantic and out there than Red Mars, but it makes for an extremely enjoyable read.

Green Mars is a story of a growing planetary population and the emergence of Mars' political foundations. Characterization and a feel for environs is a common thread throughout this book, as well as the others in the trilogy. One of the best sci-fi series I've ever had the pleasure of reading, and one that I'd highly recommend to those that are fans of more realistic sci-fi and interactions between people.