The Four Star infrared camera is a 4096 x 4096 equivalent pixel area covering the J,H,Ks bands that employs an array of four Teledyne HAWAII-2RG detectors that produce a 10.9′ x 10.9′ field of view. The instrument is currently being commissioned for the Magellan Baade 6.5m telescope at Las Campanas Observatory, Chile. Intended to provide a deep extragalactic survey capability, it is also expected to see service in more focused situations. FourStar uses an all-refractive optical system similar to the proven PANIC imager installed at Magellan. The Johns Hopkins University Instrument Development Group (IDG) played a significant role in the mechanical and opto-mechanical design of FourStar.