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In an attempt to determine if individual risk preferences change under group conditions, individuals and groups were observed when making binary decisions. The expected values of the out-comes were held constant while the probabilities of the two events varied across conditions. As previously, it was found that when the probabilities of the two events are.6 and.4, a con-servative shift is obtained. When these probabilities are.8 and-2, however, there was a tendency for groups to shift toward risk. A two-stage parameter-free model was suggested to account for individual and group choices. Current theories which deal with the so-called “risky shift ” phenom-enon (e.g., Kogan and Wallach, 1967) assume that the differences between decisions made by persons alone and in groups come about because of changes in risk preferences. It is assumed by these theories that there exist psychological processes deriving from the group situa-tion which lead the individual to change his “normal ” level of risk-taking. While there is widespread agreement that changes in individual risk preferences do indeed occur when the individual joins a group, there is no particular agreement about the psychological processes that are implicated in these changes. One theory maintains, for instance, that changes in the members ’ risk preference occur because responsibility for the decision is diffused throughout the group (Wallach, Kogan, and Bern, 1964). Another assumes that the group setting gives the individual an opportunity to Ieam that, relative to cultural standards, his risk level is lower than he previously imagined (Brown, 1965; Hinds, 1962; Stoner, 1968). Other theories assume that risk level changes because the person is more familiar with the decision problem in the group setting because ‘We are grateful to Mr. Edward J. Lichstein, who helped us in collecting and tabulating the data. 12