A self-fulfilling prophecy is a prediction that comes true at least in part as a result of a person's or group's belief or expectation that said prediction would come true. This suggests that people's beliefs influence their actions. The principle behind this phenomenon is that people create consequences regarding people or events, based on previous knowledge of the subject.

There are three factors within an environment that can come together to influence the likelihood of a self-fulfilling prophecy becoming a reality: appearance, perception, and belief. When a phenomenon cannot be seen, appearance is what we rely upon when a self-fulfilling prophecy is in place. When it comes to a self-fulfilling prophecy, there must also be a distinction "between 'brute and institutional' facts". The philosopher John Searle states the difference as "facts [that] exist independently of any human institutions; institutional facts can only exist within institutions." There is an inability of institutional facts to be self-fulfilling. For example, the old belief that the Earth is flat (institutional) when it is known to be spherical (brute) is not self-fulfilling, because Earth's shape is proven through significant evidence. There must be a consensus by "large numbers of people within a given population"—aside from being institutional, social, or bound by the laws of nature for an idea—to be seen as self-fulfilling.

A self-fulfilling prophecy can have either negative or positive outcomes. It can be concluded that establishing a label towards someone or something significantly impacts their perception and influences them to establish self-fulfilling prophecy. Interpersonal communication plays a significant role in establishing these phenomena as well as impacting the labeling process. Intrapersonal communication can have both positive and negative effects, dependent on the nature of the self-fulfilling prophecy. The expectations of a relationship or the inferiority complex felt by young minority children are examples of the negative effects of real false beliefs being self-fulfilling.

American sociologists W. I. Thomas and Dorothy Swaine Thomas were the first Western scholars to investigate this phenomenon. In 1928, they developed the Thomas theorem (also known as the Thomas dictum), stating that, "If men define situations as real, they are real in their consequences." Because of the way the couple defined a self-fulfilling prophecy, their definition was regarded as flexible in its meaning. On a societal level, there can be a consensus on what's deemed true depending on the importance of the part of the culture even if it is a false assumption and as a result of this perception of the culture it will become the outcome based on the behavior of the society. A person's perception can be "self-creating" if the belief they have is acted upon by their behavior which aligns with the outcome. Building on the Thomases’ idea, another American sociologist, Robert K. Merton, used the term "self-fulfilling prophecy" for it, popularizing the idea that "a belief or expectation, correct or incorrect, could bring about a desired or expected outcome." Robert K. Merton is typically credited for this theory because he coined the name; however, the Thomases had previously developed the theory, and the philosophers Karl Popper and Alan Gerwith had also independently contributed to the idea behind this theory in their works. Self-fulfilling prophecies are an example of the more general phenomenon of positive feedback loops.