The MDM/Ohio State/ALADDIN Infrared Camera (MOSAIC) is a general purpose near infrared (0.9-2.5 micron) imaging camera and medium-resolution (R=1300) long-slit spectrometer in use on the MDM 1.3-m and 2.4-m telescopes and the Kitt Peak 2.1-m and 4-m telescopes. In cooperation with NOAO and USNO, MOSAIC is one of the first general-purpose near-IR instruments available to the astronomical community that uses a first-generation 1024x512 ALADDIN InSb array, with the capability to use a full 1024x1024 array once one becomes available. MOSAIC provides two imaging plate scales (narrow- and wide-field), and a variety of long-slit grism spectroscopic modes. This paper describes the general instrument design and capabilities, and presents representative scientific results.