A Primer on Unrealistic Optimism

People display unrealistic optimism in their predictions about countless events, believing that their personal future outcomes will be more desirable than can possibly be true. We summarize the vast literature on unrealistic optimism by focusing on four broad questions: What is unrealistic optimism, when does it occur, why does it occur, and what are its consequences? Unrealistic optimism can be operationalized in multiple ways; is commonplace yet has well-established boundary conditions; occurs for a variety of reasons; and has consequences for affect, decision making, and behavior.