Use of interactive voice response (IVR) technology to monitor cognitive functioning in cognitively normal (CN), mild cognitive impairment (MCI), and mild dementia (MD) participants was examined using 107 community-dwelling participants, 65 to 88 years old. Baseline Clinical Dementia Ratings identified 36 participants as CN, 37 with MCI, and 34 as MD. Alzheimer's Disease Assessment Scale (ADAS) and Mini-Mental State Examinations were administered during clinic visits at weeks 0, 8, 16, and 24. IVR cognitive testing was completed at each visit and from participants' homes at weeks 4, 12, and 20. Study partners provided dementia symptoms severity ratings via IVR. The assessment system received 719 participant and 723 partner calls. All calls initiated by CN participants, 99.2% by MCI participants, and 87.3% by MD participants were completed. Telephonic Remote Evaluation of Neuropsychological Deficit tasks showed significant performance differences between participant groups, good reliability, and convergent validity with Mini-Mental State Examinations and ADAS-Cog measures. Automated cognitive testing calls took about 18 minutes to complete, and informant calls took approximately 4 minutes. IVR informant data were convergent with the ADAS-Noncog measure. Computer-automated assessments of cognitive functioning via IVR provided reliable, valid data. Such assessments might benefit routine clinical care and large-scale, longitudinal research in the future, but will require additional research over longer periods.