Standards for diaphyseal lengths of the femur, humerus, and tibia that can be used in juvenile age estimation for the ancient Maya are presented. It is argued that these new standards are necessary given differences in stature and limb proportion in Mesoamerican groups compared to the prehistoric North American groups upon whom the current available standards have been developed. Using data from 96 juveniles in the protohistoric Maya series from Tipu, Belize, regression equations were developed to predict age of dental development using diaphyseal lengths; all had excellent fit and statistical significance. When the equations were tested with diaphyseal lengths from other Mesoamerican populations, the results were supportive of such application.