The observed sexual dimorphism of velopharyngeal structures among adult populations has not been observed in the young child (4-to 9-year-old) population. The purpose of this study was to examine the age at which sexual dimorphism of velopharyngeal structures become apparent and to examine how growth trends vary between boys and girls. Method: Static 3-dimensional magnetic resonance imaging velopharyngeal data were collected among 202 participants ranging from 4 to 21 years of age. Participants were divided into 3 groups based on age, including Group 1: 4-10 years of age, Group 2: 11-17 years of age, and Group 3: 18-21 years of age. Nine velopharyngeal measures were obtained and compared between groups. Results: Significant sex effects were evident for levator length (p = .011), origin to origin (p = .018), and velopharyngeal ratio (p = .036) for those in Group 2 (11-17 years of age). Sex effects became increasingly apparent with age, with 7 of 9 variables becoming significantly different between male and female participants in Group 3. Boys, in general, displayed a delayed growth peak in velopharyngeal growth compared to girls. Conclusion: Results from this study demonstrate the growth of velopharyngeal anatomy with sexual dimorphism becoming apparent predominantly after 18 years of age. However, velopharyngeal variables displayed variable growth trends with some variables presenting sexual dimorphism at an earlier age compared to other velopharyngeal variables. N umerous studies have examined sex effects among velopharyngeal structures, particularly in the adult population. Perry, Kuehn, Sutton, Gamage, and Fang (2016) reported significant differences in velopharyngeal muscles and structures among 88 adults between 18 and 36 years of age. The authors found men demonstrated a significantly longer levator veli palatini (levator) muscle compared to women. The distance between the points where levator muscle inserts into the velar body (termed velar insertion distance) and distance between levator muscle origins was also significantly greater in men compared to women. Men were found to have a thicker and longer velum compared to women. Bae, Kuehn, Sutton, Conway, and Perry (2011) similarly reported among 10 adult participants (five men and five women) a significantly longer levator muscle among men compared to women. Perry, Kuehn, Sutton, and Gamage (2014) reported among 30 adult participants (15 men and 15 women) a significantly greater levator muscle length, greater distance between velar insertion points, and greater angles of origins. Literature supports the notion, however, that such sexual dimorphism is not found among children and may be associated with growth changes in late adolescence. Kollara, Perry, and Hudson (2016) examined 32 children between 4 and 8 years of age and did not observe sex differences in most velopharyngeal structures. Velar insertion distance was the only velopharyngeal variable found to vary based on sex, with boys demonstrating larger values than girls. A large-scale study including ...