The Optical Society of America Uniform Color Scales (OSA-UCS) possesses many salutary properties, but it is presently under-utilized. The authors believe the reason may be that the transformation from CIE notation to the OSA system presently has no known inverse. In an effort to rectify that lack, the OSA system is presented in its forward transformation, and then an inverse transformation using a NewtonRaphson iterative algorithm is described. The authors' experience with parameters associated with implementing the algorithm is related, and a few worked examples are provided to assist potential users in their implementation. (c) 2011 Wiley Periodicals, Inc. Col Res Appl, 2012; Published online 13 July 2011 in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/col.20684