The attitude construct is one of the oldest and most-studied constructs in social psychology, and as such, it has had a tremendous impact on the social sciences over the past century. This long history notwithstanding, a historical review of the attitudes literature reveals a construct whose popularity has waxed and waned over the decades and that has generated a number of passionate debates. One area of contention over the years is probably the most fundamental: what exactly are attitudes? Although the definition of the term attitude has gone through many incarnations since its early definition as a “mental and neural state of readiness” (Allport 1935, cited under General Overviews, p. 810; see also the special issue of the journal Social Cognition 25.5 for a variety of perspectives on the definition of attitudes), most current researchers use the term to refer to a valenced evaluation of something, be it a person, object, concept, event, action, etc. (i.e., the attitude object). Most theorists consider attitudes to be relatively enduring (i.e., they are typically not transitory like phenomena such as mood states); however, the extent to which they are stable and enduring would be expected to fall on a continuum, and is determined by factors such as variations in cognitive structure. Furthermore, many contemporary researchers suggest that a distinction can be made between attitudes that are deliberative and within an individual’s control, and those that are nondeliberative and automatic (i.e., explicit versus implicit attitudes). Much of the research on attitudes has focused on issues such as the structure and function of attitudes, how they influence behavior and judgment, how they can be changed, and even whether we need them and if they exist at all. The citations that were chosen for inclusion in this article were selected for a number of reasons: Some are particularly comprehensive or well-written overviews of a topic, others are seminal works or significantly advance our understanding of the construct, and still others shed light on a particular point of contention in the literature. The article begins with General Overviews, Textbooks, and selective Journals that publish high-quality attitudes research and review articles. Next, attention is turned to measurement issues in attitudes research. The largest section of the article is devoted to Attitude Formation and Change (i.e., persuasion), as this is the subtopic that has historically received the most attention from attitudes researchers, as is indicated by the corresponding volume of literature. The article then looks at attitude structure and function before concluding with coverage of the potential impact of attitudes on behavior.