Publisher Summary The chapter discusses frontotemporal dementia syndromes. Over the past decade there have been considerable advances in the understanding of neurodegenerative diseases producing focal cognitive deficits that typically involve the frontal and/or anterior temporal lobes (most commonly referred to collectively as either “frontotemporal dementia” (FTD) or “frontotemporal lobar degeneration” (FTLD). The chapter presents a classification, based on the clinical presentation and distinguishes three major clinical syndromes: frontal or behavioral variant FTD (bv -FTD), semantic dementia (SD), and progressive non-fluent aphasia (PNFA). The chapter reviews the evolution of the terms applied to this spectrum of disorders; to describe the key clinical, neuropsychological, and radiologic characteristics associated with the major syndromes; and to highlight recent developments in the genetics. In 1994, the Lund and Manchester groups introduced the term “FTD” to embrace both the behavioral and aphasic forms of focal demential and suggested tentative diagnostic criteria. Discovery of tau-gene mutations in some families with FTD lead to widespread use of the name. Apathy is the most common problem, manifesting as passivity, inertia, or inactivity together with social withdrawal. Disinhibition is a common early symptom and seems prevalent in those with right predominant frontal and temporal lobe dysfunction. Stereotypic and ritualistic behaviors such as preoccupation with counting or clockwatching, consistently choosing the same leisure activity, repeatedly eating the same food, and rigidly adherening to routine are all more common in the FTD subgroups than in Alzheimer's disease (AD). The chapter also discusses Progressive Non-Fluent Aphasia, familial frontotemporal dementia with Parkinsonism linked to chromosome 17, frontotemporal dementia with motor neuron disease, and others.