In 1992, the American Academy of Pediatrics (AAP) recommended supine sleeping to reduce the risk of sudden infant death syndrome. Although the incidence of deformational plagiocephaly is unknown, the consensus is that it has increased since this recommendation was made. To estimate the current incidence of plagiocephaly, we examined 342 infants for signs of deformational plagiocephaly, including occipital flattening, ear misalignment, frontal bossing, and facial asymmetry. Noticeable occipital flattening was documented in 15.2% of the infants (95% confidence interval, 11.6% to 19.5%); 1.46% had significant cranial deformities that also affected the skull base and face. Significant cranial asymmetry, defined as occipital flattening with concomitant skull base involvement and facial asymmetry, was observed in almost 1 in 68 infants. Adding to a growing body of evidence, our findings suggest significant increases in clinical deformational plagiocephaly since initiation of the AAP's "Back to Sleep" campaign.