A framework for estimating the impact of tourism adver tising on tourist spending is developed and implemented for the 1987-88 Ontario Incredible advertising campaign. Tour ism advertising was first linked to changes in awareness of and attitudes toward the target destination based on adver tising tracking data. Second, the changes in awareness and attitudes were linked to changes in the number of visits, based on LISREL and econometric analysis of the tracking data. Finally, changes in the number of visits were converted into changes in tourist expenditures, based on data on actual visits and expenditures. The results suggest that the returns to the advertising campaign were significant. A number of important weaknesses in the implementation are identified, together with the data that would be required to strengthen the estimates.