The General Health Questionnaire-12 (GHQ-12) is a widely used instrument for measuring psychological strain, but the factor structure of the GHQ-12 is inconclusive. The present study examined onefactor, two- and three-factor models of the GHQ-12 using structural equations modelling in a longitudinal data-set of Hong Kong employees. The findings supported a two-factor model consisting of a ‘Social Dysfunction’ factor measured by three items, and an ‘Anxiety/Depression’ factor measured by four items. Implications and limitations are discussed.