We report population data on DSM-IV Generalized Anxiety Disorder (GAD) from the Australian National Survey of Mental Health and Well-Being, obtained from a nationwide household survey of adults using a stratified multistage sampling process. A response rate of 78.1% resulted in 10,641 persons being interviewed. Diagnoses were made using the Composite International Diagnostic Interview. The interview was computerised and conducted by trained lay interviewers. We investigated comorbidity between GAD and major depressive disorder (MDD). The results indicate that sociodemographic correlates of GAD, and associated disablement and service use, are influenced by the presence of a comorbid depressive disorder but cannot be fully explained by the presence of that disorder. In addition, GAD was confirmed as significantly disabling, even as a single disorder. We conclude that the results are consistent with the view that GAD has a significant and independent impact on the burden of mental disorders.