The purpose of this study was to assess skeletal factors associated with the development of vertical facial disproportions. Angular measurements based on longitudinal lateral cephalometric radiographs of 16 male and 16 female subjects, from the ages of 4 through 18 years, were used. Subjects were selected on the basis of lower face height (ANS-Me) as a percentage of morphologic face height (N-Me). A single x-ray photograph at age 15 for the boys and 13.5 for the girls was used to classify each subject's occlusion as either open-bite or deep-bite. Sella-nasion/palatal plane, sella-nasion/mandibular plane, sella-nasion/anatomic occlusal plane, palatal plane/mandibular plane, and cranial base angle were analyzed statistically and graphically. It was found that (1) with the exception of sella-nasion/palatal plane and cranial base angles, all angular measurements demonstrated a progressive reduction throughout development in both open bites and deep bites; (2) the palatomandibular angle discriminated between open bites and deep bites throughout the developmental phase; (3) within each sex, typologic differences were evident in all angular measurements, with the exception of cranial base and occlusal plane; and (4) the cranial base angle demonstrated clear sexual dimorphism, and its magnitude was not associated with vertical dysplasia. The progressive reduction of angles in skeletal open bite reduced or maintained the magnitude of the imbalances, while the reduction of angles accentuated the skeletal deep bite with age. The inclination of the palatal plane and its constancy suggested that downward and backward rotation of the mandible in open bite subjects is precommitted in response to dentoalveolar compensatory changes with the center of rotation at the molars. The magnitude of the mandibular plane angle is not adequate for assessment of diagnostic or prognostic predictive value in determining the pattern of growth.