The design of molecular and preceramic polymer precursors to boron carbide based ceramics is described. The goal was to design nonvolatile, tractable precursors to boron carbide with high ceramic yields. Molecular precursors containing carburane cages and acetylenie groups were synthesized and converted to nonvolatile, soluble preceramic polymers. Pyrolysis of these polymers gave boron carbide based ceramics in 60–70% ceramic yield. A B4C/SiC film has been fabricated from one of the polymers and the film is uniform and crack-free.