We posit that the modern airplane is a social microcosm of classbased society, and that the increasing incidence of "air rage" can be understood through the lens of inequality. Research on inequality typically examines the effects of relatively fixed, macrostructural forms of inequality, such as socioeconomic status; we examine how temporary exposure to both physical and situational inequality, induced by the design of environments, can foster antisocial behavior. We use a complete set of all onboard air rage incidents over several years from a large, international airline to test our predictions. Physical inequality on airplanes-that is, the presence of a first class cabin-is associated with more frequent air rage incidents in economy class. Situational inequality-boarding from the front (requiring walking through the first class cabin) versus the middle of the plane-also significantly increases the odds of air rage in both economy and first class. We show that physical design that highlights inequality can trigger antisocial behavior on airplanes. More broadly, these results point to the importance of considering the design of environments-from airplanes to office layouts to stadium seating-in understanding both the form and emergence of antisocial behavior.physical inequality | situational inequality | antisocial behavior | social class | air rage R ecent media attention has been devoted to the phenomenon colloquially known as "air rage" (1, 2): a form of antisocial behavior by airplane passengers becoming abusive or unruly, antagonizing crew members and other passengers, and endangering flight safety. Such incidents can be emotionally traumatic for passengers and staff, and expensive and reputationally damaging for airlines (3). Although virtually no empirical research examines the antecedents of this hazardous and increasingly common phenomenon, popular explanations for air rage include crowded planes, frustrating delays, and shrinking seats (1, 2). We advance an alternative view: the modern airplane reflects a social microcosm of class-based society, making inequality salient to passengers through both the physical design of the plane (the presence of a first class cabin) and, more subtly, the boarding procedure (whether economy passengers must pass through the first class cabin). We hypothesize that both types of inequality on airplanesphysical (presence of first class) and situational (boarding location)-trigger antisocial behavior (negative, often aggressive behaviors that are harmful to others) (4).Since Durkheim (5), scholars across disciplines have investigated inequality and social class. The influence of social class-individuals' material resources and relative rank in the socioeconomic hierarchy-is ubiquitous, and can affect critical outcomes, such as health, well-being, emotions, and behavior (6-12). Economic scholars often conceptualize class as socioeconomic status, comprised of relatively chronic and macrostructurally determined factors, such as education, income, and geographic location (e.g....