Under the model, the most salient domain is economic availability. Research evidence overwhelmingly shows that, across the three substances, consumption declines as price increases. There is also strong evidence for including retail availability in the model. When the retail availability of alcohol and tobacco is restricted, consumption and associated problems decrease. Descriptive studies of the illicit drug market suggest that a similar relationship exists. Support for the inclusion of social availability as a domain in the model comes primarily from surveys that have found significant amounts of alcohol, tobacco, and illicit drugs are obtained through social sources. Research also provides strong support for including "promotion" in the model. Higher levels of exposure to alcohol and tobacco advertising are associated with increased consumption and problems; however, partial restrictions on advertising apparently have little impact on the promotion/use relationship; total bans are required to reduce use. Studies of efforts to enforce specific alcohol and tobacco policies provide strong evidence that enforcement can result in increased reduction of alcohol and tobacco consumption and associated problems. Significant evidence also indicates that targeting individual factors that increase a person's proclivity toward ATOD use can be effective. 249 references