Characterization of Attention Deficit Disorder (ADD) in adults has been hampered by an absence of well-defined clinical profiles on objective personality measures. A sample of 22 ADD adults completed personality testing (MMPI) in conjunction with cognitive assessment. A sample of 30 normal controls and 20 patients diagnosed with schizophrenia, who had completed the MMPI as part of a larger research protocol, were utilized as comparison groups. Validity and clinical scales revealed multiple elevations in the ADD group which were similar in nature but not to the same degree as elevations observed in the schizophrenia group. Harris-Lingoes subscales identified the sources of clinical scale elevations indicating a pattern of specific and nonspecific symptomatology which differentiated the three groups. The results may aid in identifying ADD in adults.