Metopic craniosynostosis has traditionally been reported to be the third most common form of single-suture synostosis. The purposes of this article were to analyze the relationship between metopic craniosynostosis and positional plagiocephaly and to define more clearly the differences between the changes seen with true suture fusion compared with metopic abnormalities secondary to positional changes. This is an institutional review board-approved retrospective review of three-dimensional computed tomographic scans for abnormalities of the metopic suture in all children treated at our institution for positional plagiocephaly between 1997 and 2007. We also independently reviewed the images of all patients treated for metopic synostosis for evidence of positional plagiocephaly during the same period. Among the positional plagiocephaly group, 39% were noted to have some form of metopic suture abnormality. Of the children treated for metopic craniosynostosis, a much smaller percentage also was noted to have evidence of positional plagiocephaly. Between 1997 and 2007, we treated 93 patients (50%) for sagittal synostosis, 41 patients (22%) for unicoronal, 41 patients (22%) for metopic, 4 patients (2%) for lamdoid, and 7 patients (4%) with multiple-suture involvement. This study demonstrates an increasing trend toward metopic suture abnormalities during the past 10 years, which corresponds to the same time interval of an increased incidence of positional abnormalities. It is postulated that some of these abnormalities are related to deformational forces resulting from posterior pressure. Altered mechanical forces from supine infant positioning may be associated with early metopic suture ridging and dysmorphology distinct from true craniosynostosis.