Two field studies investigated bystander intervention by witnesses to a staged shoplifting in a University bookstore. In the first study, a mass-media campaign was successful in communicating information and altering behavioral intentions, but not in increasing actual intervention behavior. A second study attempted to determine whether the low report rate and the relative ineffectiveness of the campaign to alter this rate was due to in-group loyalty between students. The results indicated that although students differentially perceived a nonstudent shoplifter, there was no increase in intervention.