A combinatorial study on the synthesis and in situ orientation of polyimide thin films by vapor deposition polymerization was carried out. The combinatorial libraries consisted of sectors with different thicknesses, compositions, and with or without alignment layers. Monomers were selected to prepare rigid rodlike polyimides and to optimize their orientation during deposition and the, imidization process. Vapor deposition of the monomers was performed sequentially or by coevaporation. By using this combinatorial approach the polymerization and the orientation behavior can be simultaneously studied and optimized by variation of film thickness, film composition, and deposition sequence.