(written from a Production point of view)
He and John J. Ordover cowrote the 1995 Deep Space Nine episode "Starship Down" and the story treatment for the 1999 episode "It's Only a Paper Moon". They also collaborated on the comic book mini-series Star Trek: Divided We Fall from WildStorm Comics.
His novels include Harbinger and Reap the Whirlwind, the first and third volumes of a new Star Trek novel series, Star Trek: Vanguard; the Star Trek: The Next Generation "Time to..." duology A Time to Kill and A Time to Heal; Warpath, part of the popular Deep Space Nine relaunch series, and the Star Trek: Mirror Universe novella "The Sorrows of Empire". Mack also contributed the additional novella "Saturn's Children" under the pseudonym Sarah Shaw. Due to a mix-up in the Pocket Books editorial department, Mack had been contracted to provide two stories in the Star Trek: Mirror Universe anthology collections. Since the offers could not be rescinded, the editors requested that Mack write one of the stories under a pseudonym, which he himself derived – Shaw. Mack noted that working under the pseudonym "freed me up, in a sense, to approach Saturn's Children with a different style. I wrote it much more quickly than I normally do, and by imagining I was a different author I ended up working from a different mindset. It was an intriguing experience.". 
Mack has also worked with Keith R.A. DeCandido on the Star Trek: Starfleet Corps of Engineers eBook series, contributing the two-part novels Invincible (collected in Miracle Workers) and Wildfire, as well as the single volumes Failsafe (collected in Grand Designs), and Small Worlds (collected in Creative Couplings).
His Star Trek short stories include the Shinzon story "Twilight's Wrath", in the Tales of the Dominion War anthology, and the Zak Kebron story "Waiting for G'Doh, or, How I Learned to Stop Moving and Hate People", in the Star Trek: New Frontier anthology No Limits. Another short story - "For Want of a Nail" - appeared in the 2009 Mirror Universe anthology Shards and Shadows.
Mack's most extensive project is the crossover trilogy Star Trek: Destiny, released in late 2008, which featured characters from a number of Star Trek series, and affected the story lines of most of the ongoing novel series.
2009 saw Mack pen the fifth novel in the Vanguard series, Precipice, and the Mirror Universe novel The Sorrows of Empire (an expansion of his earlier novella, doubling the length of the original), as well as a tie-in novel to The 4400.
Mack's latest projects include the first novel in the Star Trek: Typhon Pact miniseries, Zero Sum Game, one of four novellas in the Vanguard collection Declassified, and the culmination of the Memory Omega storyline in the Mirror Universe series, Rise Like Lions.
On 9 March 2011, Mack revealed that he had signed contracts with Pocket Books for four more Trek novels to be released in 2012 - the eighth installment in the Vanguard series, Storming Heaven, and the Star Trek: The Next Generation - Cold Equations trilogy. 
Mack's contribution to the series of books set after Star Trek, More Beautiful Than Death, is currently "on hold" - along with the other planned releases in that series - following executive decisions at Pocket .
- DS9: "Starship Down" (writer, with John J. Ordover)
- DS9: "It's Only a Paper Moon" (story, with John J. Ordover)
- Pocket TNG
- Pocket DS9
- Star Trek: Starfleet Corps of Engineers
- Star Trek: Vanguard
- Star Trek: Mirror Universe
- Star Trek: Destiny
- Star Trek: Typhon Pact
- Star Trek
- Tales of the Dominion War - "Twilight's Wrath"
- No Limits - "Waiting for G'Doh, or, How I Learned to Stop Moving and Hate People"
- Shards and Shadows - "For Want of a Nail"
- Declassified - "The Stars Look Down"
- Star Trek: Deep Space Nine - The Fallen (dialog)
- Star Trek: Deep Space Nine - Dominion Wars (dialog)
- Star Trek: Starship Creator (character biographies)