Psychologists concerned with judgment and decision making have often considered why people make systematic deviations from normative models, but they have generally failed to consider sociocultural factors that influence these decisions. This research will consider why casino blackjack players in Las Vegas, Nevada and Prague, Czech Republic play systematically differently from one another and from a well-known normative model in order to build a model of judgment and decision making that takes culture into account. Other games will be considered for comparative purposes, and beginning gamblers will be distinguished from experienced ones. In addition to ethnographic fieldwork within the gambling subcultures in each country, open-ended interviews and structured surveys will be used.