Jim Stahler has been involved in Squad Leader and Advanced Squad Leader for nearly half a century. He was one of the original playtesters for both Squad Leader and ASL and he has been a playtester for all of the Squad Leader modules and many of the ASL modules. He has written numerous articles about ASL published in the Avalon Hill General, the ASL Annual, and the ASL Journal. He has updated the majority of the original scenarios from Squad Leader to ASL. He has drawn on his vast experience with the game system to create a comprehensive book focused on ASL, The ASL Companion.

The ASL Companion is far more than just a rehash of the rules. This work discusses the components and the play of ASL. It explains the rules in a more conversational format than the Rulebook, and it often lists several scenarios that feature the rules being discussed, to allow players to give those rules a try.

It also discusses how and when to apply the rules to the play of the game, and in some cases it gives the motivation for the rules. It includes loads of examples to supplement the examples in the ASL Rulebook, and lots of analyses of probabilities, since luck lies at the heart of ASL.

The ASL Companion is not a substitute for the Rulebook. Rather, consider it a commentary on the Rulebook. The intent of The ASL Companion is to serve as a guide to ASL, to make the rules easier to understand, and to make the more obscure parts of the game become more accessible to the ASL player.