The second major revision of the Dungeons & Dragons Basic Set was variously promoted as the Revised Second or Third edition. It was frequently called the "red box" until the release of the next red-boxed Basic D&D game. Unlike Holmes' earlier Basic Set, Moldvay's version was marketed as a separate line, not as an introductory set intended to introduce players to Advanced D&D (or OD&D's 3-Volume Set ).

While Moldvay's "purple/magenta" box still only allowed players to run characters from levels 1–3, it became the first truly stand-alone edition of BD&D with the simultaneous release of the Expert Set (the two sets together are known as the "B/X" version of D&D) which allowed characters up to 14th level. Also unlike Holmes' version (which is more closely related to OD&D), Moldvay's rules are distinct from both of the other D&D lines, and served as the foundation for all subsequent games in the "Basic" or "Classic" line, which remained in print until 1999.