The book summarizes the scientific information gathered over the past 20 years from direct observation of planetary atmospheres. The opening chapters describe the origin of the Sun and Solar System bodies, and the mechanisms which control atmospheric structure and characteristics during the evolutionary process. The primary evolutionary atmospheric histories of the planets and major satellites are described. The history of the Earth's atmosphere is traced, with particular reference to the origin and evolution of life on Earth. The final chapters review shorter-term atmospheric changes, the stability of planetary environments, exobiology and the complexity of evolutionary processes, using climatic models.