The Galactic Milieu Series is a series of science fiction novels by Julian May. It is linked to her previously-published series, the Saga of Pliocene Exile; and through the fantastical device of time-travel, acts as both a prequel and a sequel to this earlier series. The "Galactic Milieu" of the title is an interplanetary federation, and Earth's membership of it is a central plot concern. The series involves several religious and philosophical themes, including references to the work of Pierre Teilhard de Chardin.