Formal models and conventional wisdom converge on the idea that the strategy and tactics of major-party opponents in presidential campaigns should vary as a function of the competitive situation in which the two sides find themselves. That idea forms the core of our interpretation of the circumstances underlying negative campaigning. We test it by analyzing the statements of the presidential and vice-presidential candidates in the 1960 through 2000 campaigns. The data are consistent with our interpretation. Strategically, tickets were most likely to go on the attack in races in which they were running far behind. Tactically, vice-presidential candidates were most likely to out-attack their presidential running mates in races in which their ticket was running far ahead. Close contests in which neither side enjoyed a clear or enduring lead seemed to complicate strategic choices for both tickets and thereby to confound the tactics of presidential and vice-presidential candidates.