The study found that the techniques used could not distinguish sex from the lower jaws of the immature skulls. Still, some of the findings were close to statistical significance, which suggests that a further increase in sample size might produce morphometric evidence of sex from the lower jaw of subadults. Current results, however, indicate that sex can only be determined from the lower jaw from subjects approximately 15 years old and older. Confirmation of this estimate is required by using adequate skeletal samples of individuals from 10 to 17 years old from a single population. The entire sample of 96 subadult lower jaws were from 3 distinct populations whose sex, local population, and age were documented. A total of 38 bilateral 3-dimensional landmarks were designed and acquired by using a Microscribe G2X portable digitizer and Inscribe-32 software. Landmarks where chosen to correspond with those commonly used in traditional metrical and geometric morphometric systems. In addition, a series of new landmarks were designed to characterize the shape of the posterior ramus, lateral body, and symphyseal region. The shape analysis software "morphologika" was used to analyze the three-dimensional coordinates of the landmarks. Multiple regression was used to determine any statistically significant difference in measurements. Measurement error in landmark acquisition was assessed by digitizing six different specimens on six occasions. 3 tables, 2 figures, and 35 references