A modular hand guard assembly serves both as a hand guard system and as an integrated interface system for mounting various weapon accessories and attachments thereto. The modular hand guard assembly includes a removable forward rail section that can be removed from the forward portion of the hand guard to provide for the installation of additional weapon accessories such as lights, optics or lasers in highly a desirable forward location adjacent to the barrel of the weapon. The modular hand guard assembly further includes an integrated modular switching and control system for use in connection with the various powered accessories mounted thereto.