This thesis aims at revealing the register of Barack Obama and Hillary Clinton’s 2008 presidential campaign speeches in Pennsylvania primary, the similarities and differences between the speeches, and the relationship between the speakers’ gender and the applied register. This research belongs to descriptive, qualitative, comparative research applying total sampling technique. The transcripts documents of Obama and Hillary’s 2008 presidential campaign speeches in Pennsylvania primary were selected as the source of data. The data were examined by using content analysis to reveal several results. First, in terms of field, Obama and Hillary used the campaign speeches as a media to inform and persuade the audiences by exploring physical actions to reveal what happened during the presidential campaign and things they will do as the next president. However, Obama tried to persuade the audiences by using mental perceptions covering his thought and believe while Hillary used her personal viewpoints. Second, in terms of tenor, the status between the speakers and the audiences is equal due to the dominant use of proposition clauses used to give information. Unequal status also occurred when Obama demanded services from the audiences by using direct command showing men’s assertiveness while Hillary used indirect command showing women’s positive politeness. Third, in terms of mode, Obama and Hillary shaped their speeches by using familiar words, tend-to-be-spoken style, the involvement of the audiences and one-way communication.