Wide field-of-view, high-resolution near-infrared cameras on 4-m class telescopes have been identified by the astronomical community as critical instrumentation needs in the era of 8-m and larger telescopes. Acting as survey instruments, they will provide the input source discoveries for large-telescope follow-up observations. The NOAO Extremely Wide Field Infrared Mosaic (NEWFIRM) imaging instrument will serve this need within the US system of facilities. NEWFIRM is being designed for the National Optical Astronomy Observatory (NOAO) 4-m telescopes (Mayall at KPNO and Blanco at CTIO). NEWFIRM covers a 28 x 28 arcmin field of view over the 1-2.4 μm wavelength range with a 4k x 4k pixel detector mosaic assembled from 2k x 2k modules. Pixel scale is 0.4 arcsec/pixel. Data pipelining and archiving are integral elements of the instrument system. We present the science drivers for NEWFIRM, and describe its optical, mechanical, electronic, and software components. By the time this paper is presented, NEWFIRM will be in the preliminary design stage, with first light expected on the Mayall telescope in 2005.