Abstract Objective Difficulties managing medications, particularly among older adults experiencing cognitive deficits, is an important contributing factor to medication nonadherence that may have significant negative financial and health outcomes. The current study examined the performance of healthy older adults’ (HOA) and individuals with amnestic mild cognitive impairment (aMCI) on the medication management abilities assessment’s (MMAA, a performance-based measure of medication management) original scoring criteria and derived error process measures, assessing medication overtaking and undertaking magnitude. Exploratory correlations between performances on the MMAA and self-reported confidence in medication management skills and cognitive abilities were also examined. Method A sample of 25 HOAs with aMCI and 25 age- and education-matched HOAs completed the MMAA, a self-reported medication management confidence rating and a battery of neuropsychological tests. Results HOAs performed significantly better on the MMAA score and committed significantly less process errors than individuals with aMCI. Despite these differences in MMAA performance, the HOA and aMCI groups rated similar high levels of confidence in their ability to manage a new medication routine. Notably, while the HOA group’s performance on all of the MMAA measures did not relate to cognitive measures, the aMCI group’s performance on the MMAA score was significantly related to memory and executive functioning and a new process error score for overtaking was related to processing speed. Conclusions Although these results present promising potential for the MMAA as a measure of medication management in a clinical setting, further studies need to examine the validity of the MMAA against real-world adherence measures.