Lebanese secondary school students' conceptual profiles in physics are evaluated by comparison to their U.S. peers, in an attempt to ascertain the effectiveness of the Lebanese physics curriculum currently in place. A conceptual profile consists, among others, of conceptions and dispositions that students develop about a particular discipline. A battery of three instruments were developed and validated to assess student profiles in particular areas of physics. Two instruments, the Inventory of Basic Conceptions in Mechanics and the Inventory of Basic Conceptions about DC circuits, targeted student conceptions in classical mechanics and electricity respectively. A third instrument, the physics form of the Views About Science Survey, targeted student dispositions about knowing and learning physics. The three instruments were administered to over three thousand Lebanese and U.S. students between 2004 and 2007. Results show that Lebanese students: (a) enter secondary school encumbered with naive conceptual profiles that are at odds with scientific paradigm, (b) fail, after physics instruction, to enhance their profiles and develop them to the level aspired for in the official curriculum, and (c) lag, in most conceptual respects, behind their U.S. peers.