The authors report the development of a monolithic diamond field emission device in lateral configuration operating in a vacuum package. Nanocrystalline diamond is applied in the microfabrication of planar lateral emitter diodes on a silicon-on-insulator substrate. A feasible packaging process has been developed for the device, where the diodes are die attached, wire bonded, and vacuum sealed in a cavity package. Field emission characterization measurements performed on the packaged diamond lateral vacuum devices indicate a practical construct and package for vacuum micro/nanoelectronic applications. (C) 2009 American Vacuum Society. [DOI: 10.1116/1.3039686]