Hairlines change shape with age, starting at birth. A good head of hair is frequently present some time after ages 3 to 5 years. The look of childhood has its corresponding hairline, and, as the child grows and develops into adulthood, facial morphology migrate changes from a childlike look to a more mature look. This article discusses the dynamics of hairline evolution and the phenotypic variations of the front and side hairlines in men and women. A modeling system is introduced that provides a common language to define the various anatomic points of the full range of hairlines.