In the first criterion-related validity study of a complete 360-degree competency assessment process (i.e., where customer data are included), aggregated 360-degree assessment of 428 retail associate store managers on six competencies showed strong validity (.50) in the prediction of assessment center performance. In addition, 360-degree assessments on each of the six competencies were significantly correlated with the criteria. The aggregated 360-degree assessments also demonstrated incremental validity over managerial ratings alone in the prediction of assessment center criteria. Customer (mystery shopper) assessments were also significantly correlated with the assessment center criteria and exhibited incremental validity beyond supervisory assessments. © 2006 Wiley Periodicals, Inc.