Warranting Theory proposes that third-party testimonials are more influential in online impression formation than target-authored statements. Individuals posting content on social media accurately convey their offline personality while endeavouring to present themselves in a positive light. In doing so they may misjudge the psychological distance of the majority of viewers, who could view this positive self-presentation as bragging and form resultant negative impressions. In this study, we asked 136 participants to view the Facebook timelines of four female targets. Timeline content varied by source (owner- vs. friend-authored) and focus (generally positive vs. personally positive). Participants were tasked with forming impressions of targets and rating them on attractiveness, confidence, modesty, and popularity. We found that source and focus played distinct roles in impression formation. More positive impressions were formed when owner-authored content was general, and when friend-authored content was personal. This highlights the role played by content focus on impression formation, and the potentially damaging effect of perceived bragging. These results are discussed in relation to the application of the Warranting Theory of impression formation online, and discrepancies between these results and those from related articles are examined.