Greater numbers of instructors are turning to social networking sites to communicate with students. This study examined whether posting social, scholarly, or a combination of social and scholarly information to "Twitter" has an impact on the perceived credibility of the instructor. Participants were assigned to one of three groups: a group that viewed social tweets, one that viewed scholarly tweets, and one that viewed a combination of social and scholarly tweets. Participants were then asked questions about the instructor's perceived credibility. Results show that participants who viewed only the social tweets rated the instructor significantly higher in perceived credibility than the group that viewed only the scholarly tweets. No other significant differences were found among the groups. These results have implications for both teaching and learning, as there is an established link between perceived instructor credibility and positive learning outcomes. (Contains 5 tables and 1 figure.)