Scenes in movies where smoking occurs have been empirically shown to influence teenagers to smoke cigarettes. The capacity of a Canadian warning label on cigarette packages to decrease the effects of smoking scenes in popular movies has been investigated. A 2 × 3 factorial design was used to test the effects of the same movie scene with or without electronic manipulation of all elements related to smoking, and cigarette pack warnings, i.e., no warning, text-only warning, and text + picture warning. Smoking-related stereotypes and intent to smoke of teenagers were measured. It was found that, in the absence of warning, and in the presence of smoking scenes, teenagers showed positive smoking-related stereotypes. However, these effects were not observed if the teenagers were first exposed to a picture and text warning. Also, smoking-related stereotypes mediated the relationship of the combined presentation of a text and picture warning and a smoking scene on teenagers’ intent to smoke. Effectiveness of Canadian warning labels to prevent or to decrease cigarette smoking among teenagers is discussed, and areas of research are proposed.