Consumer footprints left on the Internet help advertisers show consumers relevant Web ads, which increase awareness and click-throughs. This “proof of concept” experiment illustrates how Internet behavior can identify relevant television commercials that increase ad-effectiveness by raising attention and ad exposure. Product involvement and prior brand exposure, however, complicate effective Internet-targeting. Ad relevance matters more for low-involvement products, which have a short pre-purchase search process. For the same reason, using Web browsing behavior to make inferences about current ad relevance is more accurate for low-involvement products. Prior brand exposure reduces information-value, even for relevant commercials, and therefore dampens ad relevance's effect on attention and ad exposure.