Do negative advertisements lower voters’ evaluations of the targeted candidate? We theorize that there is much to be gained by examining the variance in the content and tone of negative campaign messages and the variance in voters’ sensitivity to negative political rhetoric. We employ data from the 2006 Cooperative Congressional Election Study to investigate the impact of negative campaigning in U.S. Senate campaigns. We sampled 1,045 respondents in 21 of the 28 U.S. Senate races featuring a majority party incumbent and challenger. In addition to the survey data, we collected contextual data regarding the political advertisements aired during the campaigns and the news coverage of these campaigns in state newspapers. The evidence suggests that the impact of negative information is multifaceted, and under some circumstances, substantial. We find that uncivil and relevant negative messages are the most powerful, especially for people with less tolerance for negative political rhetoric.