One of the major roles of the skull is to protect the brain from physical injuries. To accomplish this critical condition, the cranial vault functions as a dome‐shaped structure composed of both inner and outer tables of cortical bone and diploe in between, suggesting independent biomechanical purposes for every stratum. However, questions regarding how the combination of the external and internal mechanical properties of these components in the cranial vault would maximize its capabilities to undertake functional loadings and minimize the employment of bone mass have not been systematically studied. We hypothesized that bone mass and elastic properties are different between two cortical layers. In this study, twelve pairs of the cortical samples from the parietal bone of a female baboon were collected, with each inner‐outer cortical paired sample from the same site. Cortical thicknesses and densities were measured, and elastic properties were assessed using ultrasonic technique. Results demonstrated remarkable difference in both thickness (F= 1.131, p 蠄0.05) and density (F=0.274, p= 0.015) between inner and outer paired samples. Differences in orthotropic elastic behavior (E 1 and E 3 ) were found between two cortical layers as well. How these differences are linked to the stress environments of the inner and outer cranial cortical layers awaits further studies. Grant Funding Source : Supported by NSF BCS‐0725183, and COLCIENCIAS (Bogotá, Colombia).