The Kessler Psychological Distress scale (K10) is an instrument that is widely used to screen for mental disorders, but information is lacking on its psychometric qualities in non-Western samples. This study used a population-based sample (N = 725) to assess the reliability and validity of the K10 across ethnic groups in an urban area. The results were generally supportive of the K10 as a reliable and valid instrument to screen for anxiety and depression in all three groups. Cronbach's alpha was high (0.93) and the results indicated the existence of a solid single factor structure. Item bias in relation to ethnic background was minor. In each group, there was good criterion validity with respect to one-month DSM-IV diagnosis for depressive and/or anxiety disorder. The results nevertheless highlight the importance of cross-cultural validation, as we found different cut-off values for ethnic subgroups to obtain optimal sensitivity and specificity for detecting depressive and/or anxiety disorders. Copyright © 2009 John Wiley & Sons, Ltd.