Ok this comes with some caveats and explanation, but Agents of Influence will be the 100th five year mission, TOS branded, original book published by S&S! This counts every full length novel set in the 5YM, plus Constellations, both 5YM ebooks which have been published under the TOS brand, and the two YA novels from the 80s. This doesn't count novelizations, or any other non-original publications, nor does it cover novellas or short stories published as part of a larger work. And I didn’t count In Tempest's Wake, which was branded Vanguard. You can see the exact listing on my revamped "How Many Five Year Mission Adventures Are There?" page here. Congrats to @Dayton Ward for a cool milestone!