1. Foundation series
1951 - Foundation
1952 - Foundation and Empire
1953 - Second Foundation
1982 - Foundation's Edge
1986 - Foundation and Earth
1988 - Prelude to Foundation
1991 - Forward the Foundation
2. The Robots series
1950 - I, Robot (story collection)
1954 - The Caves of Steel
1957 - The Naked Sun
1982 - The Complete Robot (story collection)
1983 - The Robots of Dawn
1985 - Robots and Empire
1986 - Robot Dreams (story collection)
1990 - Robot Visions (story collection)
3. Galactic Empire series
1950 - Pebble in the Sky
1951 - The Stars, Like Dust
1952 - The Currents of Space
1955 - The End of Eternity
1989 - Nemesis
1992 - The Positronic Man