Gamma Hydroxybutyrate (GHB) was banned from the consumer market by the Food and Drug Administration in 1991. Despite the ban, use of GHB has continued to contribute to thousands of emergency department visits and numerous fatalities in recent years. Efforts to reduce the use of this drug have had limited impact, which may be the result of using traditional prevention strategies that focus exclusively on educating people about of negative consequences of substance use rather than addressing the factors that motivate use. In an effort to identify motivational factors that could be targeted in future prevention efforts, the present study was designed to examine outcome expectancies for GHB that may promote use of this drug. Methodology that has led to successful strategies to reduce alcohol use was applied to identify GHB expectancies and model cognitive processes likely to encourage or discourage GHB use. Individual differences scaling was used to empirically model a two dimensional semantic network of GHB expectancies stored in memory, and preference mapping was used to model likely paths of expectancy activation for male and female GHB users and nonusers. Differences in expectancies between GHB users and nonusers followed patterns previously identified in relation to alcohol expectancies and alcohol use. Conclusions were limited by relatively low numbers of GHB users in the sample, despite the use of a very large number of participants, overall. Despite this limitation these findings lay the groundwork for development and validation of GHB expectancy based prevention strategies.