The crystal structure of the carbamazepine-S-naproxen cocrystal was solved using powder X-ray diffraction and density functional theory calculations, providing insight into the arrangement of molecules in the crystal lattice and the hydrogen bonding network. This research contributes to the understanding of pharmaceutical cocrystals, which have the potential to improve the physicochemical properties of active pharmaceutical ingredients, such as aqueous solubility, dissolution, hygroscopicity, and bioavailability. The large unit cell volume and lattice parameters in this cocrystal are related to the intricate arrangement of the molecules within the crystal lattice, which is often observed in pharmaceutical cocrystals. Key Takeaways: 1. The crystal structure of the carbamazepine-S-naproxen cocrystal was solved using powder X-ray diffraction and density functional theory calculations. 2. The complex arrangement of molecules in the crystal lattice and the hydrogen bonding network of the cocrystal were analyzed. 3. The large unit cell volume and lattice parameters are common in pharmaceutical cocrystals and are related to the intricate arrangement of molecules within the crystal lattice.