We examined the psychometric properties of the Assessment of Depression Inventory (ADI). This instrument assesses depression and also has validity scales that address response honesty. Three studies were conducted. The first describes the development of the ADI. The second compared the concurrent validity of the ADI Depression (Dep) scale with the BDI-II, and the ADI Feigning (Fg) scale responses of psychiatric inpatients with those of a sample of community volunteers asked to feign depression. The third study was used to cross-validate the results with a separate sample of participants. The ADI Dep scale correlated highly with the BDI-II. Significant differences were also found between the honest patient responders and the non-patient feigners on the Fg scale. The data supports the ADI validity scales as measures of response style and the Dep scale as a measure of depression.