Online social networking (OSN) sites play many roles ranging from communication to entertainment. The current paper presents an analysis of the recently emerged OSN phenomenon of the selfie (self-portrait photographs of oneself). In two studies involving a total of 1296 men and women, we tested the prediction that selfie-sharing on various OSN sites (including Facebook) is positively related to social exhibitionism, extraversion, and self-esteem. Participants reported sharing anywhere between 0 to 650 selfies per month on various OSN sites, and were found to post, on average, 2.9 selfies of themselves, 1.4 selfies with a romantic partner, and 22 group selfies to Facebook each month. Women posted more selfies of each type than did men. Regardless of sex, our results indicate that social exhibitionism and extraversion generally predicted the frequency of online selfie-posting in men and women, however we found no strong evidence for a relationship between self-esteem and selfie-posting behavior among women, and only weak evidence among men. The results of this work highlight key individual differences among OSN users that can account for some of the variation in online photo sharing behavior, and provide novel insight into the psychological factors driving this rapidly popularizing phenomenon. (C) 2015 Elsevier Ltd. All rights reserved.