INTRODUCTION: Subjective cognitive decline (SCD) in older adults is a condition with a complex phenomenology and diverse etiologies including (but not limited to) mood, personality, and health concerns, as well as biomarkers of preclinical Alzheimer's disease such as amyloid-β deposition and gray matter volume loss. Approximately 60% of affected persons are estimated to decline to Alzheimer's dementia. Regardless of etiology, persons with SCD may be optimal targets for early intervention. OBJECTIVE: To ascertain the feasibility and impact of mindfulness training (MT) as an early intervention in persons with SCD. METHODS: Using a single-blind, randomized controlled trial design, older adults with (n = 14) and without (n = 22) SCD were randomized to either MT or a control condition of psychoeducation (PE) on cognitive aging. EEG/ERP (specifically, the P3 component), structural MRI, and self-report measures of psychological functioning were obtained within 4 weeks prior to and within 2 weeks following intervention. RESULTS: MT resulted in decreased reaction time intra-individual variability for all participants, with a selective increase in the P3 event-related component for those with SCD. Compared with PE, MT also resulted in an increase in percent volume brain change in structural MRI. Finally, all SCD participants reported a decrease in cognitive complaints and increase in memory self-efficacy following intervention. DISCUSSION: Results suggest that MT is a feasible early intervention in persons with SCD. Longer-term follow-up with larger sample sizes will determine whether MT can slow the rate of decline in persons who may be at risk for Alzheimer's dementia.