Current marketing research on response to entry assumes that an incumbent decision maker faces potential rivals one at a time as in a series of duels. In many circumstances, however, an incumbent decision maker faces a large number of entrants simultaneously (a “battle royale”). An experiment using experienced managers shows that the increased complexity produced by multiple entrants had a significant effect on the managers' decision processes and their decision outcomes. Specifically, when faced with multiple entrants, the managers adopted more noncompensatory decision processes, and were more likely to misidentify the most threatening entrant as defined by their self-explicated weights or conjoint part-worths. These results provide insight into an unexplained gap between the extant normative and empirical research on response to entry. © 2003 Wiley Periodicals, Inc.