The Functional Theory of Political Campaign Discourse was first proposed by William Benoit (1996), and it is now frequently used to analyze the discourse of political debates and the functions of political utterances in debates. The present thesis applies Benoit‘s Functional Theory to analyze the texts of the 2012 American presidential debates. Overall, the results showed that Acclaims (59.5%) were the most frequently-used function, followed by Attacks (32.7%) and then Defenses (7.8%). Policy (94.2%) was discussed significantly more commonly than Character (5.8%) in these debates. When discussing Policy, the candidates discussed Past deeds (48.1%), Future plans (33.3%), and General goals (12.7%). When discussing Character, they uttered Personal qualities (0.5%), ideals (2.3%), and leadership ability (3.1%). Moreover, the incumbent candidate Obama acclaimed significantly more and attacked less than the challenger Romney. Finally, both Obama and Romney put great emphasis on Past deeds and Future plans, but paid relatively less attention to General goals.