PLOS Medicine recently compiled this special collection of PLOS articles dedicated to research on dementia. This collection may be of interest to researchers and health care professionals, as well as those who know someone personally affected by dementia. This special collection is guest edited by Dr. Carol Bryane, director of the Cambridge Institute of Public Health, and Dr. Bruce Miller, director of the Memory and Aging Center at the University of California, San Francisco. Featured articles include a synthesis of available medical research for Alzheimer's disease; an analysis of different kinds of rehabilitative therapy for individuals with dementia; and an investigation of dementia diagnosis in the Netherlands over a course of 22 years. In addition, Eric B. Larson and Kenneth M. Langa's article, "What's the 'Take Home' from Research on Dementia Trends?", offers a helpful analysis of the Dutch study's significance for members of the general public.