American company Ace Books began publishing genre fiction starting in 1952. Initially these were mostly in tête-bêche format with the ends of the two parts meeting in the middle and with a divider between them which functioned as the rear cover of both (the two parts were oriented upside-down with respect to each other in order to effect this), but the company also published some single volumes during the early years. The proportion of singles increased until they stopped producing doubles about 1978. The tête-bêche format was discarded in 1973, but future double novels were continued for a while with both parts oriented the same way, so that the first page of one part followed soon after the last page of the other part.
Between 1952 and 1968, the books had a letter-series identifier; after that date they were given five-digit numeric serial numbers. The list given here includes every Ace Double Book published between 1952 and 1978, for all genres. It gives a date of publication; in all cases this refers to the date of publication by Ace, and not the date of original publication of the novels. For more information about the history of these titles, see the entry for Ace Books, which includes a discussion of the serial numbering conventions used and an explanation of the letter-code system.
Because the tête-bêche format is part of the attraction for some collectors, titles published between 1974 and 1978, which contained two titles by one or two authors but which are not tête-bêche, are not regarded by some collectors as true Ace Doubles. All the books are included in the list given below, with the difference in format noted.
The list given here includes an indication of the genre of the works, in italics after the serial number. Abbreviations used are "SF" for science fiction titles; "MY" for mystery titles, and "WE" for westerns. In addition, "NA" is used to mean "not applicable", when one or both of the books is not in one of these three genres; and "UN", when the genre of the books is not known. The list also gives a date of publication; in all cases this refers to the date of publication by Ace, and not necessarily the date of original publication of the novels.
The list is thought to be complete, but there may be minor omissions among the later lists.
For more information about the history of these titles, see Ace Books, which includes a discussion of the serial numbering conventions used and an explanation of the letter-code system.
Ace Image Library. Contains images of most covers for the doubles in all genres, as well as many of the single titles.
Bookscans. Contains numerous images of the Ace covers.
Corrick, James A. Double Your Pleasure: The Ace SF Double, Gryphon Books, 1989. ISBN0-936071-13-3. A historical article, followed by a checklist of the SF Doubles, giving prior publication history for the contents of each one.
Thiessen, J. GrantScience Fiction Collector #1, Pandora's Books, 1976. Includes Ace Double checklist.
Thiessen, J. GrantScience Fiction Collector #2, Pandora's Books, date unknown. Includes errata for checklist in #1.
Tuck, Donald H.The Encyclopedia of Science Fiction and Fantasy: Volume 3, Advent: Publishers, Inc., 1982. ISBN0-911682-26-0. Lists all ACE sf titles, single and double, published through 1968.
The following references have not been reviewed:
Jaffery, SheldonDouble Trouble: A Bibliographic Chronicle of Ace Mystery Doubles, Starmont Popular Culture Series no. 11, Borgo Press, 1987. ISBN1-55742-118-8.
