The document summarizes Donald C. Hambrick's Upper Echelon Theory. The theory proposes that executives make decisions and act based on their own personal experiences and interpretations of situations rather than objectively. It also argues that the collective characteristics of a company's top management team are more predictive of organizational outcomes than any individual executive. The theory was refined over time to include the concepts of managerial discretion and behavioral integration of the top management team. Empirical evidence from several studies provided support for aspects of the theory. Challenges remain in fully understanding the cognitive mechanisms by which executive characteristics influence decisions.