Other researchers have demonstrated that the following eight nonmetric traits of the ilia and mandible differentiate the sexes in subadults: elevation of the auricular surface, angle of the greater sciatic notch, depth of the greater sciatic notch, the "arch criteria," curvature of the iliac crest, gonial eversion, mandibular protrusion, and mandibular arcade shape. The current study examined these features for 85 pre-Colombian subadult mummies that ranged in age between newborn and 15 skeletal years of age. The sex of each mummy had been determined by a team of pathologists through a visual inspection of both external and internal sex organs during standard autopsy procedures. The current study examined each of the eight traits for each of the mummies to determine whether it was different according to sex within age classes; and the study further sought to determine which of the eight traits are sufficiently accurate to be useful in forensic cases. The study found that all eight of the traits were related to sex, but there was significant variation within each sex and between age classes in terms of the strength of congruent sex-related associations. With the exception of gonial eversion, all of the traits produced statistically significant X squared value for their associations with known sex when all subadult remains were considered; however, when all subadults were considered, only the four following traits demonstrated acceptable levels of accuracy for forensic purposes: the arch criteria (82.3 percent), angle of the sciatic notch (80.7 percent), depth of the sciatic notch (79 percent), and mandibular arcade shape (77.6 percent). For the mummies that ranged in age from newborn to 5 skeletal years of age, only depth of the sciatic notch (81.5 percent) and the arch criteria (81.5 percent) approached acceptable levels of accuracy for use in forensic cases. The implications of these results are discussed, and recommendations for bioarchaeological and forensic applications are offered. 9 tables and 22 references