Langford assisted in producing the second edition of "The Encyclopedia of Science Fiction" (1993) and contributed some 80,000 words of articles to "The Encyclopedia of Fantasy" (1997). He is one of the four chief editors of the third, online edition of "The Encyclopedia of Science Fiction" (launched October 2011), and shared this reference work's 2012 Hugo Award for Best Related Work. He has also edited a book of John Sladek's uncollected work, published in 2002 as "Maps: The Uncollected John Sladek". Langford's critical introduction to "Maps" won a BSFA Award for nonfiction. With Christopher Priest, Langford also set up Ansible E-ditions (now Ansible Editions) which publishes other print-on-demand collections of short stories by Sladek and David I. Masson, and review columns by Algis Budrys.