The lower third of the face is often an afterthought in aesthetic plastic surgery. Aging across the mandibular border may be described by several mechanisms: fat atrophy and volume loss; shifting of subcutaneous fat compartments; and mandibular septum dehiscence with submandibular fat hypertrophy. Accurate diagnosis of the apparent mechanism of jaw line aging is critical to successful facial rejuvenation. Diagnosis directs the plastic surgeon as to which key anatomic components in this region to manipulate to optimize rejuvenation. The senior author's technique for facial rejuvenation across the mandibular border is described with an algorithm for facial rejuvenation of the jaw line. Several consistent patterns of facial aging are apparent and a theory of their mechanism is suggested: (1) patients with thin skin and minimal jowling resulting from fat atrophy; (2) jowl ptosis with normal skin and loss of submalar hollow and midface fullness, caused by displacement of fat compartments; and (3) cascading confluent fat over the mandible, produced by septum dehiscence. Fat atrophy is treated with fat replacement, either injectable or autologous fat. Jowl ptosis is treated with septum release and superficial musculoaponeurotic system elevation to restore jaw line definition. Confluent fat is treated by septum release, superficial musculoaponeurotic system elevation, and direct excision of fat over the mandible. Application of techniques without proper analysis and definition may lead to an operated look with a swept jaw line. Undertreatment may not achieve jaw line definition.