Rationale and study aims: Persons with mild cognitive impairment (MCI) experience declines in everyday functioning and cognitive performance greater than what is experienced in normal aging but less than that of dementia. Daily stress and daily memory complaints associated with cognitive deficits may contribute to greater psychological distress in the day-to-day experiences of persons with MCI. However, research examining the occurrence of daily stressors, daily memory complaints and psychological distress in MCI is limited, and it is not clear how the daily processes of stress and affect in persons with MCI compare to cognitively healthy older adults. This dissertation examined the occurrence of daily stressors, daily memory complaints, retrospective and daily well-being in persons with MCI compared to cognitively healthy controls. Main analyses examined whether daily stressors and daily memory complaints were associated with worse daily affect in MCI participants compared to controls, and whether increased daily stress was associated with a greater number of memory complaints. Methods: The study used a short-term repeated measures design, and included MCI and control participants recruited from a university-based memory clinic. The interviews consisted of a baseline interview and up to eight consecutive days of brief daily phone interviews. The interviews included both retrospective and daily measures of psychological well-being, daily stressors, daily memory complaints, and open-ended questions about daily experiences. Results: Persons with MCI reported a greater number of daily memory complaints and worse psychological distress, as measured by both retrospective and daily reports. There were no significant differences between MCI and control participants, however, in the frequency of daily stressors. In both unadjusted and adjusted analyses, on days when a participant reported more daily stressors, they had higher negative affect. The stress-negative affect relationship was stronger for MCI participants compared to controls. MCI and control participants who reported more memory complaints, on average, had higher negative affect. Discussion: Daily stressors were disproportionally associated with greater psychological distress in MCI participants as compared to cognitively healthy controls. Interventions targeting the potential distress associated with daily life may be beneficial for psychological well-being in persons with MCI. Future research should examine other potential mechanisms of distress in daily lives of persons with MCI in order to inform relatives and caregivers of persons with MCI, clinicians who give diagnoses to their patients, and individuals providing community support for individuals living with MCI.