A consonant smile line, in which the incisal edges of the maxillary anterior teeth are parallel to the upper border of the lower lip, is a key component of dentofacial esthetics for both dentate and edentulous patients. The angle of the occlusal plane is the primary determinant of an optimal smile, and modifying this angle through prosthetic, restorative, or orthodontic therapy is the most effective way to enhance smile esthetics. This article reviews the parameters and methods used to establish the ideal smile line for dentate and edentulous subjects. (Am J Esthet Dent 2012;2:188–198.)