The activities of daily living (ADL) functioning of 26 subjects with Alzheimer's disease was measured using the Assessment of Motor and Process Skills (AMPS) and family informants' Older Americans Resources and Services (OARS) Activities of Daily Living (ADL) reports. Concordance with a clinician's ratings of subjects' level of ADL functioning was achieved for 77% of the subjects based on their AMPS ADL process ability measures and for 54% for the subjects based on their family informants' OARS ADL ratings. In cases of discordance, subjects' AMPS ADL process ability measures were just as likely to overestimate (11.5%) as to underestimate (11.5%) subjects' ADL functioning. In contrast, 46% of the informants overestimated their family members' ADL functioning, and this was more likely to occur when subjects' cognitive impairment was mild.