Galaxy and If were initially published by separate companies. However, in 1963, both titles were acquired and published by the same company.

Galaxy was published from 1950 until 1979. A single issue was published when it was resurrected in 1980.

The British edition went through numerous resurrections. Its first run lasted from 1953 until 1962. It was then brough back for several issues in 1967 and again from 1969 until 1970. Its final run lasted from 1972 until 1975.

The Galaxy Science Fiction Novel was a series of individual novels printed in the same digest format as the magazine. This series lasted from 1950 until 1961. The Galaxy Magabook was probably an attempt to bring back the format. Two issues, each featuring two novels, were published in 1963.

If was published from 1952 until 1974. The placement and appearance of the "Worlds of" and "Science Fiction" elements changed frequently, such that it was possible to believe the name was 'IF Worlds of Science Fiction', 'Worlds of IF Science Fiction', 'Worlds of IF' or 'IF Science Fiction'. The title itself was unique enough that this hardly matters.

The British edition went through numerous incarnations: the first run lasted from 1953 until 1955. It was then resurrected from 1959 until 1962, again for several issues in 1967, once more from 1969 until 1970 and its final run lasted from 1972 until 1974.

Worlds of Tomorrow was published from 1963 until 1967, when it was combined with IF as IF Worlds of Science Fiction Combined with Worlds of Tomorrow. It was then briefly resurrected under its own name for several issues between 1970 and 1971.

The World of If Reader and Best Science Fiction From Worlds of If were anthology reprints published in digest size.

Worlds of Fantasy, four issues were published between 1968 and 1971.

International Science Fiction saw two issues produced in 1967, publishing translated works.