Previous research on fear/threat appeals has correlated fear intensity with persuasion. However, fear might influence persuasion in at least four conceptually distinct ways: (a) the proclivity to experience fear, (b) the rise from baseline to peak, (c) peak intensity, and (d) the decline from peak to postmessage fear. A study was conducted in which 361 participants read a message that first described the dangers of influenza, then advocated obtaining a free vaccination. Significant positive correlations were observed between tonic, that is, traitlike, activation of the behavioral-inhibition system (BIS) and various indices of fear arousal. Nonsignificant correlations were observed between the behavioral-activation system (BAS) and the same indices. Both rise and peak measures of fear predicted persuasion, but decline in fear had no discernible impact on persuasion. © 2004 Wiley Periodicals, Inc.