The global population is aging rapidly. This demographic shift towards an older population poses a major public health challenge and highlights the need to identify strategies to support healthy aging. Prior research has suggested that green space may promote cognitive health, but there are gaps in knowledge that limit the application of findings in planning and policy to optimize health benefits. In this work, we will use long-term data on aging to study the influence of residential green space exposure on cognitive decline and dementia among middle-aged and older adults. We will advance existing knowledge by studying the health impacts of specific green space types and forms of contact, as well as pathways linking green space to health outcomes. We will use these findings to develop and apply an index of green space characteristics that are supportive of healthy cognitive aging that may be used by urban planners to direct the design of greening strategies. We will communicate our research findings to scientists, policy makers, and the public. Our aim is to help guide the creation of urban planning and public health policies that improve population health. This work will help to advance initiatives to support healthy aging.