Voters and political candidates increasingly use social networking sites (SNSs) such as Facebook. This study uses data from an online posttest-only experiment (N = 183) in analyzing how exposure to supportive or challenging user comments on a fictional candidate's Facebook page influenced participants’ perceptions of and willingness to vote for the candidate, as well as whether candidate replies to each type of user comments affected these outcomes. Participants who viewed a page with supportive comments and “likes” reported more favorable perceptions of and greater support for the candidate, relative to participants who viewed a page with challenging comments. Thus, the appearance of interactivity between a candidate and other users on the candidate's Facebook page can shape the responses of those viewing the page. However, exposure to candidate replies to either supportive or challenging comments did not lead to significantly more favorable perceptions or a greater likelihood of voting for the candidate.