The objectives of this study are to develop a brief self-rated screening instrument for generalized social anxiety disorder (GSAD) and to test the efficiency of the instrument. The Social Phobia Inventory (SPIN), a 17-item self-administered scale for GSAD, was given to 263 individuals with GSAD and controls. A subset of three items yielding high sensitivity and specificity for the diagnosis of GSAD was identified. This abbreviated version of the SPIN (Mini-SPIN) was administered to a group of managed care patients in conjunction with an epidemiological study of GSAD. Patients (n = 7,165) were sent a questionnaire comprising the Mini-SPIN and a brief depression screener. Respondents screening positive for GSAD on the Mini-SPIN (n = 344) were interviewed using the social phobia module of the Structured Clinical Interview for DSM-IV (SCID) to verify the diagnosis. A random sample of those who screened negative for GSAD on the Mini-SPIN were administered a similar interview to identify two control groups without GSAD for comparison (n = 673). With this information, the sensitivity, specificity, and positive and negative predictive values for the Mini-SPIN were determined (weighted for sampling). Using a cutoff score of 6 or greater, the Mini-SPIN demonstrated a sensitivity of 88.7%, specificity of 90.0%, positive predictive value of 52.5%, and negative predictive value of 98.5%. The scale possessed 90% accuracy (efficiency) in diagnosing the presence or absence of GSAD in a managed care population. The Mini-SPIN demonstrates good efficiency, supporting its utility as a screening tool for generalized social anxiety disorder. Copyright 2001 Wiley-Liss, Inc.