Social networking sites (SNSs) have recently become integrated in modern lives as entertainment, communication, and even careers have become more reliant on them. The current study explored the relationship between Facebook and Twitter attachment and demographic, motivation, and personality traits. Differing psychological relationships may explain why people become more attached to specific SNSs as well as explain their continuance of use. Using online self-report measures, this study measured motivations to use Facebook and Twitter, the Big Five personality traits, and Facebook/Twitter attachment of 109 participants who have been users of both Facebook and Twitter. Results of hierarchical multiple regressions showed that conscientiousness, extraversion, neuroticism, and openness to experience were unable to explain a significant amount of attachment to Facebook or Twitter. Facebook attachment was explained by the motivation to pass time and interact socially whereas Twitter attachment was explained by the motivation to pass time and share information. These findings can help media researchers, as well as companies, understand why people become attached to various SNSs