Diamond films and islands have been synthesized with varying defect densities and dopant levels by chemical vapor deposition for field emission display applications. Vacuum field emission measurements show that the electric held required to induce electron emission from diamond can be significantly reduced when the samples are properly grown or postgrowth processed so that they contain a substantial amount of structural defects. The defective diamond is characterized by a broadened peak at 1332 cm(-1) in Raman spectroscopy with a full width at half-maximum in the range of 7-11 cm(-1). These materials require a turn-on field (for a current density of 0.01 mA/cm(2)) as low as 15 V/mu m, and a threshold held (for a current density of 10 mA/cm(2)) as low as 30 V/mu m for electron emission. These field values are almost an order of magnitude lower than those required for high quality, p-type semiconducting diamond. Detailed numerical analysis of the emission current-voltage data from multiple diamond tips with varying geometric and electronic properties is presented, and the mechanisms responsible for such low voltage electron emission from defective diamond are discussed.