Preliminary studies of interdiagnostician agreement have shown that the DSM-III holds promise for improving diagnostic reliability. This study examined the characteristics of five DSM-III diagnostic categories (schizophrenia, mania and schizotypal, narcissistic and borderline personality disorders) with respect to three psychometric criteria. Examined were the specificity, syndrome association and internal consistency of the diagnostic criteria for these disorders. Results suggested that of the diagnostic categories examined, the criteria for schizophrenia performed best under empirical scrutiny, while criteria for borderline and narcissistic personality disorders were more problematic. Suggestions are made for subsequent investigations into the internal validity of DSM-III. 1985.