Growth of highly oriented, (100)-textured diamond films has been achieved through a multistep growth process which included biasenhanced nucleation and textured growth. The grain misorientation was analyzed by polar X-ray diffraction, electron diffraction and analysis of the dislocation spacing at a small-angle grain boundary. The electronic properties of simultaneously deposited, randomly oriented polycrystalline; highly oriented, (100) textured, and single-crystal homoepitaxial diamond films were compared to assess the role of grain boundaries. Calculations suggest that the highly oriented, (100)-textured film possessed a lower density of interfacial traps by about 50% compared with randomly oriented polycrystalline diamond film. This reduction in interfacial traps in the highly oriented, (100)-textured film could account for the mobility improvement by a factor of 3 over the mobility of the polycrystalline film. The homoepitaxial film possessed a mobility three times that of the highly oriented, (100)-textured film, and it appeared that additional reductions in trap density should provide additional opportunities for improved mobility in highly oriented, (100)-textured films.