The invention is a device for removable placement in the mouth, which advances the lower jaw and draws the tongue forward and upward, thereby providing relief for snoring and obstructive sleep apnea. The device includes an upper portion, the upper surface of which is adapted for engagement with the users upper dentition. A downward extension, suspended from the anterior part of the upper portion, features an anterior surface that engages the back of the lower front teeth, so as to advance the lower jaw forward with respect to the upper jaw. The posterior surface of the downward extension features a rearward extension, which is curved upward at its lateral margins to meet the upper portion, so as to define, with the hard palate of the user, a cavity that is sized and shaped to snugly engage the users tongue. Within the defined cavity, the device preferably features a soft elastomeric surface.