The Las Campanas Infrared Survey Camera is a near-infrared (1.0-2.5 lm), wide-area instrument used to detect and measure the photometric properties of galaxies out to large redshifts, z > 2. The camera, a modified Offner 1 : 1 reimaging optical system, is mounted at the f/7.5 focus of the 2.5 m du Pont Telescope. The detectors are four Rockwell 1024 Â 1024 HgCdTe (HAWAII) arrays operating at a scale of 0>20 pixel À1 . With four telescope pointings, the instrument produces a pipelined mosaic of

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... , H, or K s images 13 0 Â 13 0 on the sky, with a measured point-spread function as good as 0>38 FWHM. The good imaging quality results in part from fast tip-tilt guiding on stars within a 9 0 Â 9 0 field centered on the optical axis of the telescope. Appropriately bright guide stars are found within 2 s from a catalog of 5 Â 10 7 stars and presented as a " finding chart " to the observer. The optical, mechanical, and thermal design choices and their associated engineering implementations are discussed in some detail. The detector readout electronics, the automatic data acquisition and control system, and our data reduction pipeline are also described. The design goals of the camera-excellent imaging quality and throughput, low flexure and internal background, and 5 Hz on-axis guiding, are all realized and quantified.