The overarching goal of this project is to rigorously test the efficacy of mindfulness training as a cognitive rehabilitation tool to mitigate age-related cognitive decline. Although the last decade has seen an increase in the number of cognitive training studies in the elderly, the majority of studies focus on computerized task-specific cognitive training, resulting in enhanced performance on the task being trained, but weak transfer to other tasks in the same domain and no transfer to other domains. The proposed study, employing mindfulness training as a cognitive rehabilitation tool, is novel in its reconceptualization of traditional cognitive training approaches into a training program that first and foremost promotes concentrative attention, thereby targeting attentional control, and secondly, does so in a framework that cultivates acceptance and non-reactivity, thus prioritizing older adults' increased socioemotional drive for emotional well-being and satisfaction. Our main hypothesis is that eight weeks of training in practices of mindfulness meditation, designed to increase concentrative attention and reduce the wandering tendencies of the mind, will increase performance on tasks of attentional control in the elderly, partially via mindfulness-induced neuronal plasticity in the intrinsic functional architecture of the brain. Using a single-blind, randomized controlled design, 120 older adults ages 65-85 will be assigned to either a mindfulness-based stress reduction (MBSR) group or an active lifestyle education control group matched for therapist contact time, engagement with the material, format of the intervention, a combination of experiential and didactic components, and perceived cognitive benefits. Assessments of dependent variables will be completed at pre-training, post-training, and then at a 12-month follow-up session. In Aim 1, we will investigate the short- and long-term impact of MBSR training on behavioral and neural correlates of attentional control (Aim 1.a and 1.b), and then examine the mediating role of mind-wandering and default-mode network connectivity in yielding attentional control benefits (Aim 1.c). Aim 2 investigates the efficacy of MBSR for far-transfer to abilities contributing to quality of life: broad laboratory- based and everyday measures of cognition (Aim 2.a), and emotion regulation strategies (Aim 2.b). The proposed work will establish the causal link between engagement in mindfulness practices and improved attentional control as well as identify reduced mind-wandering and default-mode network integrity as potential mechanisms of action through which mindfulness training exerts its effect on attentional control. Not only will the current study design offer an easily disseminable and cost effective treatment for cognitive decline in older adults, it will also provide a theoretical mechanism on which to base future cognitive rehabilitation designs, advancing the field of rehabilitation as a whole.