The study examines the influence of national culture on national averages of time spent (ATS) visiting the largest social networking sites (SNSs): Facebook, Twitter, and LinkedIn. The analysis uses cultural dimensions adopted from both the works of Hofstede and Schwartz, while controlling for country e-readiness and median population age. The findings suggest that culture's influence may be moderated by the media richness and type of network focus of each SNS. Overall, in rich-media SNSs, egalitarianism positively impacts ATS. Individualism and masculinity only impact ATS on friendship-oriented SNSs. Additionally, uncertainty avoidance and intellectual autonomy only impact ATS on professional-oriented SNSs.