He has lived in several countries and currently resides in the United States in New Mexico with his wife Jan. Stirling, along with Eric Flint, was tuckerized as a Secret Service agent in John Birmingham's alternate history WWII novel Weapons of Choice (2004).

In addition to his books' military, adventure, and exploration focus, he often describes societies with cultural values significantly different from modern Western views.

One of his recurring topics is the influence of the culture on an individual's outlook and values, with an emphasis on the idea that most people and societies consider themselves moral.

The Draka, for instance, choose and face a different imperative in their conquest of Africa, and turn earlier to breech-loading firearms and steam power than the rest of the Western world.

[3] In the past, he has frequently collaborated with other authors, including David Drake, Jerry Pournelle, Anne McCaffrey, and Raymond E. Feist.