The Beginner Box Set is designed as the entry point into the game for new BattleTech players. The quick-start rules, which can be learned in under an hour, will have new players quickly slugging it out in the thirty-foot-tall war machines known as BattleMechs. The longer introductory rules provide more extensive guidelines for 'Mech movement and combat as well as construction rules for building or customizing your own (introductory-level) 'Mechs. Quick-start rules for vehicles and infantry are also included for players interested in combined-arms battles. Also included in the box set is a BattleTech universe book providing an overview of the game world, its history, and its factions. A set of 2 unpainted plastic 'Mechs, ready for play and suitable for painting, are accompanied by prefilled record sheets listing each 'Mech's capabilities. The set also includes maps, a painting and tactics guide, cardstock reference sheets, a universe poster map of the BattleTech universe, and two six-sided dice.

The 2011 "Twenty-Fifth Anniversary Edition" of the box set replaces the 2007 edition's thin paper maps with board game-style mounted maps, adds two "high-quality" plastic minis (a Thor and a Loki (and accompanying record sheets), and includes a brief guide detailing the BattleTech gaming system intended to introduce new players to the various products for the game.