Vacuum packaging of high performance infrared (IR) MEMS uncooled detectors and arrays, inertial MEMS accelerometers and gyros, and radio frequency (rf) MEMS resonators is a key issue in the technology development path to low cost, high volume MEMS production. Wafer-level vacuum packaging transfers the packaging operation into the wafer fab. It is a product neutral enabling technology for commercialization of MEMS for home, industry, automotive, and environmental monitoring applications. 4 in. wafer-level vacuum packaging has been demonstrated using IR MEMS bolometers and results will be presented in this article. In addition to the wafer-level packaging results, vacuum package reliability results obtained on component-level ceramic vacuum packages will also be presented.