Linear regression techniques and continuous norming were used to develop a procedure to estimate age-adjusted WAIS IQ scores from the Shipley Institute of Living Scale. The estimation procedure was derived on a mixed sample of 86 psychiatric patients and then was replicated on an independent sample of 44 psychiatric outpatients. Estimated scores based on the cross-validation sample correlated .76 and .74, respectively, with WAIS Full Scale scaled scores and IQs and did not over- or underpredict, which indicates a high degree of concordance between these two procedures. Compared to other procedures, such as those employed by Paulson and Lin (1970b), the continuous norm estimates of age-adjusted IQ are more stable because the age norms are smoothed analytically rather than developed on separate age groups. Thus, this estimation procedure is recommended for use in clinical and research settings in which a brief but accurate IQ estimate is desired.