CMS jet and Etmiss commissioning

We describe how jets and met are defined, reconstructed, and calibrated in CMS, as well as how the CMS detector performs in measuring these physics objects. Performance results are derived from the CMS simulation application, based on Geant4, and also from noise and cosmic commissioning data taken before the first collision event was recorded by CMS in November 2009. A jet and met startup plan is in place which includes a data quality monitoring and prompt analysis task force to identify and fix problems as they arise.