This chapter reviews the existing scholarship on agenda setting, focusing on two aspects of human choice. The first aspect centers on behavioral analyses of choice, especially cognitive limits to rationality (e.g., limits to the human attention span, the process of satisficing, and the use of heuristics), directed at understanding how individuals prioritize action. The second aspect focuses on organizational choice, with an emphasis on the impacts of information processing, search processes, and organizational structure. The chapter examines linkages between micro and macro processes, showing how studies of organizations and broader political systems based on a model of comprehensive rationality fail. Focusing on behavioral foundations allows for a more accurate and holistic explanation of issue prioritization (agenda setting) in complex organizations based on behavioral models of choice. The chapter concludes with suggestions for future directions of research.