Although a hemangioma may be present at birth, it usually becomes apparent within a few weeks of life as a small erythematous macular patch or localized telangiectasia, with growth occurring over the following few months (Figure 1). This rapid phase of growth is referred to as the proliferative phase and continues through ages 8 to 12 months, with the most rapid growth usually occurring during the first 3 to 6 months. It is during this rapid proliferation that functional problems (ie, visual impairment, airway obstruction, and/or ulceration) and cosmetic deformities first become apparent. While some hemangiomas increase only slightly in size, others rapidly enlarge, resulting in a very disfiguring lesion. Predicting which lesions will rapidly proliferate is best done by performing serial examinations and/or determining a history of rapid expansion over weeks or months. The proliferative phase is followed by the involuting phase, which begins between ages 8 and 12 months, but can begin as late as ages 18 to 20 months in some patients. During the involution phase, the tumor rate of growth is proportionately less than the growth rate of the child. Involution is characterized by a reduction in firmness of the hemangioma and a change from a shiny, bright red appearance to a grayish mottled appearance as the vascularity of the lesion becomes replaced with fibrofatty tissue. Involution occurs over the next 1 to 12 years of childhood, and the rate of involution is highly variable, as is the resulting cosmetic deformity. The difficulty and challenge in managing these lesions arises from trying to predict which children will have a substantial deformity at the time they enter school. Equally challenging is determining at what point one should intervene, and with what treatment modality.