The history of the Merril Collection goes back to August 10, 1970, when an agreement was signed between Judith Merril, a prominent science fiction author/editor, and the Board of the Toronto Public Library. In this agreement Judith Merril donated to the Toronto Public Library her collection of science fiction, fantasy, and associated non-fiction which contained around 5,000 items. This collection was named The Spaced Out Library.

The Spaced Out Library was established as a reference collection of "contemporary speculative literature, including science fiction, certain aspects of fantasy fiction, satire, surrealist, and other speculative, future oriented, and conceptually experimental work, whether in fiction, poetry, drama, essay, or other forms as well as critical and bibliographic materials relating to science fiction and the associated areas of contemporary speculative writing" serving both scholars and the general public.

For the first five years the collection was located in the Palmerston Branch at 566 Palmerston Avenue, Toronto, later moving into Boys & Girls House at 40 St. George St., where the growing number of books (from 5,000 to 17,000 items) found more space.

In 1990 the collection was officially renamed The Merril Collection of Science Fiction, Speculation and Fantasy.

Throughout the years the collection continued to grow to its present size of approximately 57,000 items and soon outgrew its location at 40 St. George St. In 1995 it was moved to the new location at 239 College St., Toronto, Ontario, into a new "state of the art" building.

The Merril Collection's book stacks are temperature- and humidity-controlled to prolong the life span of the materials and preserve them for future generations. The attractive reading room displays original science fiction art, current periodicals, recent acquisitions, and changing exhibits of library materials. There are also study carrels, lockers and a quiet room for small groups. The building also features three programme rooms which can be reserved for conferences and meetings.

The Merril Collection is now recognized as Canada's major collection of speculative fiction and one of the world's finest popular culture collections. It is unique in that it is also Canada's only collection of this type that is open to the general public, as well as to the academic community.

In 1995 the Merril Collection co-sponsored an exhibition on Canadian science fiction and fantasy, Out of this World, at the National Library of Canada.