Persuasive appeals posted to United States presidential candidates’ YouTube videos were coded using a grounded theory mixed-methods design. 37,562 comments about education, energy, Iraq, health care, the economy, and the presidential debates were randomly collected by date and time for three studies using coding analysis: pilot, presidential primaries, and the presidential election. Seven argument types were identified and theoretically refined according to dual process models of persuasion: reason-based, candidate-based, emotion-based, endorsements, enthusiasmheuristic, other-interest and self-interest. Theoretical comparisons and hypothesis testing of argument types were conducted by issue and election event. Consistent with impression involvement, reason-based appeals were more frequent during the primaries, whereas consistent with value and outcome involvement, emotion- and candidate-based appeals were more frequent during the election.