The Dark Energy Survey (DES) will be a survey of 5000 square degrees to griz of 24th mag and observations of ~10 square degrees to gri of 24th mag every ~2 nights. The goal of the survey will be to constrain w and dw/dz to <10% by measuring the spatial distribution of clusters at 0.1 < z < 1.3, the shifting of the galaxy spatial angular power spectra with redshift, weak lensing on several redshift shells to z~1, and ~2000 type Ia supernovae at 0.3 < z < 0.8. Other interesting astronomical science is also expected to arise from the data. DES will be executed on the CTIO Blanco 4m telescope using a new, wide-field, prime focus CCD camera. The Dark Energy Camera (DECam) will have a 2.2 degree diameter field-of-view covered by 520M 0.27 arcsec pixels and extremely good red response.