From the start, Ballantine was one of the leading publishers of paperback sf, publishing both novels and short sf such as the respected Star Science Fiction series edited by Frederik Pohl. In the early 60s, Ballantine published J. R. R. Tolkien's Lord of the Rings in paperback, a work which would sell tens of millions of copies. In 1969, Lin Carter launched the Ballantine Adult Fantasy series, which brought many rare fantasies back into print. During the mid-1970s, Ballantine published the first Star Trek books using writers such as Alan Dean Foster.
In 1977, Ballantine set up Del Rey Books as a science fiction and fantasy imprint under the editorship of Lester del Rey and his wife Judy-Lynn to rival Donald A. Wollheim's launch of specialist science fiction publisher DAW Books.
Today, Ballantine and Del Rey are known as Ballantine Del Rey.