Abstract: An oral appliance and method for reducing snoring including upper and lower mouthpiece portion, each of which having a rigid structural core and a relatively soft outer portion which may be conformed to fit the upper teeth of the user. The upper and lower mouthpiece portions are first mounted on a holder with the upper mouthpiece portion positioned forward a desired offset amount from the lower mouthpiece portion (preferably about 3.0 mm). The entire assembly is then heated and the outer soft material of the upper and lower mouthpiece portions softens and may be placed in the mouth to permit the mouthpiece portions to be conformed to the upper and lower teeth. Once the upper and lower mouthpiece portions have been properly fitted, the assembly is removed from the mouth and allowed to set into a permanent state. The upper and lower mouthpiece portions are then removed from the holder and attached directly to one another without any offset therebetween forming the full mouthpiece.