This chapter discusses the potential role that vascular risk factors and asymptomatic cerebrovascular disease (CVD) may have on lifetime risk for dementia. It examines evidence regarding the extent and character by which vascular cognitive impairment (VCI) influences cognition and by what mechanism VCI may contribute to incident dementia whether the dementia syndrome results from Alzheimer's disease (AD), vascular dementia (VaD) or a mixed dementia. The chapter reviews the concept of VCI, and also discusses the spectrum and potentially long time course of vascular-related brain injury, and the potentially important role of cerebral white matter in relation to widely distributed cognitive processes such as memory. It addresses cognitive changes associated with aging, and the potential role of asymptomatic vascular brain injury in these processes. The chapter outlines the identification of clinically relevant episodic memory impairment (amnestic mild cognitive impairment (aMCI)) due solely to presumed brain vascular disease.