The authors sampled registered voters who had, and had not, voted in a vote-by-mail special election. They tested Ansolabehere and Iyengar's (1995) conclusion that attack ads mostly discourage independents from voting and reinforce the loyalties of Republicans and Democrats. Democrat Ron Wyden, the narrow winner of the election, pledged late in the campaign that he would no longer ‘go negative.’ Republican Gordon Smith did not follow suit. Only Republicans's participation clearly fell with reported exposure to Smith's attack ads. Republicans, independents, and Democrats who felt Wyden had lived up to his pledge were more likely to vote for Wyden.