A modular helmet interface with a mounting cleat, threaded insert, and adhesive layer is provided. In one aspect, a mounting cleat is affixed to a helmet, such as a ballistic helmet, by an adhesive layer, the mounting cleat having an outer portion and a threaded insert within a cavity formed in the outer portion. The outer portion has an inward facing surface configured to receive an adhesive layer for coupling the inward facing surface to the helmet surface. In another aspect, a mounting cleat is secured to a helmet by way of a cleat-receiving securing member, the securing member affixed to the helmet by an adhesive layer. In a more limited aspect, a helmet having multiple mounting cleats configured to support an accessory mounting rail or a helmet mount assembly.