A sequel to Emergence, Tracking, was serialized in three parts, beginning in the July/August 2008 issue of Analog. Tracking was continued in the September issue and concluded in the October issue of the magazine.
His second novel, Threshold (ISBN 0-553-24878-2), was published as the first book in the To Halt Armageddon trilogy in 1985, to somewhat lesser acclaim. The "About the Author" section of Threshold states that David is "currently working on the sequel to Threshold, also to be published by Bantam", to be called Spēcial Education, although it has not been published to date. He stated in the afterword to the 1990 edition of Emergence that any future writing would depend upon his finances. Palmer has another completed but unpublished novel, Schrödinger's Frisbee, which is not related to either of his first two novels. Wormhole Press has been indicated as a possible publisher for the new novels and for a reprinting of the Emergence and Threshold
Jay Kay Kline's "Biolog" for David R. Palmer appeared in the February 1983 Analog Science Fiction and Fact with the novella "Seeking", p 61.