Their work as editor includes the Cambridge Companions to science fiction and fantasy, collaborations with Edward James.

They have served as editor and chair of the science fiction journal Foundation, and as the president of the International Association for the Fantastic in the Arts.

In 2015, Mendlesohn received the SFRA's Clareson award for distinguished service to the science fiction field.

[4] Mendlesohn joined Staffordshire University in November 2016 as professor and assistant dean in law, policing, forensics & sociology,[5] and is now an associate fellow of the Anglia Ruskin Centre for Science Fiction and Fantasy.

The book traces the development of children's fantasy from the 16th to the 21st centuries, covering events such as the collection of folk tales, the impact of world wars, and the emergence of young adult fiction.

[10] In 2005, Mendlesohn won the Hugo Award for Best Related Work for The Cambridge Companion to Science Fiction, which edited with historian Edward James.

[11] In 2010, Mendlesohn was nominated twice for the Best Related Work Hugo, for The Inter-Galactic Playground: A Critical Study of Children's and Teens' Science Fiction, and for On Joanna Russ.