Abstract Two studies tested the effects of TV ads with celebrity endorsement on the product preference and understanding of 8- to 14-year-old boys. Study 1 compared two ads for a model racer. One had celebrity endorsement (by a famous race driver) and footage of real automobile racing featuring the celebrity (live action); the second had neither feature. Study 2 employed one ad for a different brand of model racer edited to generate a 2 (endorser presence) by 2 (inclusion of live racetrack action) factorial design. A total of 415 boys were exposed to one of the experimental ads or a control ad, embedded in a new animated children's adventure program. Preference for the advertised brand of model racer (pre- and postviewing) and a number of cognitive variables were assessed. Exposure to endorsement led to increased preference for the toy and belief that the celebrity was expert about the toy. Live action led to exaggerated estimates of the physical properties of the toy and the belief that the ad was not staged. The 8- to 10-year-olds associated the glamour of the endorser with the toy and were more reliant on his advice than were 11- to 14-year-olds. However, the two age groups were not differentially affected by the ads. Contrary to the speculation of many researchers, understanding about advertising intent and techniques and cynicism about ads had almost no influence on product preference after viewing.