We report on the development of ARCONS, the ARray Camera for Optical to Near-IR Spectrophotometry. This photon counting integral field unit (IFU), being built at UCSB and Caltech with detectors fabricated at JPL, will use a unique, highly multiplexed low temperature detector technology known as Microwave Kinetic Inductance Detectors (MKIDs). These detectors, which operate at 100 mK, should provide photon counting with energy resolution of R = E/δE > 20 and time resolution of a microsecond, with a quantum efficiency of around 50%. We expect to field the instrument at the Palomar 200" telescope in the first quarter of 2011 with an array containing 1024 pixels in a 32×32 pixel form factor to yield a field of view of approximately 10×10 arcseconds. The bandwidth of the camera is limited by the rising sky count rate at longer wavelengths, but we anticipate a bandwidth of 0.35 to 1.35 μm will be achievable. A simple optical path and compact dewar utilizing a cryogen-free adiabatic demagnetization refridgerator (ADR) allows the camera to be deployed quickly at Naysmith or CoudÂ´e foci at a variety of telescopes. A highly expandable software defined radio (SDR) readout that can scale up to much larger arrays has been developed.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.