The interrater agreement for major diagnostic categories in studies using DSM-I and DSM-II was usually only fair or poor. In phase one of the DSM-III field trials the overall kappa coefficient of agreement for axis I diagnoses of 281 adult patients was .78 for joint interviews and .66 for diagnoses made after separate interviews; for axis II--personality disorders and specific developmental disorders--the coefficients of agreement were .61 and .54. The interrater reliability of DSM--III is, in general, higher than that previously achieved and may be due to changes in the classification itself, the separation of axis I from axis II conditions, the systematic description of the various disorders, and the inclusion of diagnostic criteria.