Alzheimer’s disease (AD) and vascular dementia (Va D) are commonly viewed as the first and second most common types of dementia, respectively. The traditional paradigm has been to view and treat each illness as a separate entity with a separate pathophysiology. However, clinical and pathological studies suggest that the boundary separating AD and Va D, as well as their mild cognitive impairment (MCI) analogs, is not well defined. Thus, there is increased interest in viewing these diseases along a spectrum because of the significant overlap in the characterization and diagnosis of AD, Va D, and MCI. The focus of this edited volume is to examine how AD and Va D, as well as their MCI analogs, are best viewed as a heterogeneous, intersecting, if not a continuous disease state rather than separate, distinct entities. This book examines this approach by providing empirically based evidence, reviews of the literature, and chapters by key leaders in the field and will be of interest to clinical neuropsychologists and anyone studying or treating dementia in its many forms.