The first part of this article focuses on summarizing the empirical findings on dream content, such as the universality of dream themes, the specific but general dream elements, and the occurrence and content of bad dreams and nightmares. The second part of the article reviews the currently influential theories explaining dream content data, for instance, psychoanalytic theories, random activation theories, continuity hypothesis, psychological healing function of dreams, and several theories on the evolutionary functions of dreams. © 2009 Elsevier Inc. All rights reserved.