Net Force Explorers (with Russell Davis)
17. Cloak and Dagger (2002)

Twilight Zone
3. Deep in the Dark (2004)

Shadowrun (with Jean Rabe)
Aftershock (2006)

Murder Most... (with Martin H Greenberg)
Murder Most Medieval: Noble Tales of Ignoble Demises (1993)

Fantastic (with Martin H Greenberg)
Warrior Fantastic (2000)
Knight Fantastic (2002)

Black Cats and Broken Mirrors (1998) (with Martin H Greenberg)
Alien Abductions (1999) (with Martin H Greenberg)
Future Crimes (1999) (with Ed Gorman, Martin H Greenberg)
Star Colonies (2000) (with Ed Gorman, Martin H Greenberg)
Villains Victorious (2001) (with Martin H Greenberg)
The Mutant Files (2001) (with Martin H Greenberg)
Space Stations (2004) (with Martin H Greenberg)
Little Red Riding Hood in the Big Bad City (2004) (with Martin H Greenberg)
In the Shadow of Evil (2005) (with Martin H Greenberg)
Slipstreams (2006) (with Martin H Greenberg)
Army of the Fantastic (2007) (with John Marco)
Man Vs Machine (2007) (with Martin H Greenberg)
Future Americas (2008) (with Martin H Greenberg)

The Valdemar Companion (1990) (with Mercedes Lackey)
The Valdemar Companion: A Guide to Mercedes Lackey's World of Valdemar (2001) (with Denise Little) (see Mercedes Lackey)
Alpha Bravo Delta Guide to the U.S. Navy (2003)
Unauthorized Dan Brown Companion (2006) (see Dan Brown)