Frontotemporal dementia is a new name for clinical Pick's disease; the eponymic term PiD has been increasingly restricted to the pathologic variant with Pick bodies. This article describes the clinical picture, pathology, and genetic mechanisms of frontal lobe dementia. Frontotemporal dementia is still under-diagnosed and underestimated, partly because the individual components of the complex are considered separately or are considered "heterogeneous," a somewhat misleading adjective used in many descriptions. This article emphasizes the considerable overlap among the different varieties of frontotemporal dementia, as well as the distinctive features of each.