摘要:This article draws on findings from semi-structured interviews to investigate an important, and previously unexplored aspect of the social networking site Twitter, which is the ways that users can employ lateral surveillance to initiate friendships. Social penetration theory (Altman and Taylor 1973) is used to investigate the ways that Twitter provides a platform to technologically augment friendship evolution. Three consecutive phases of online surveillance are proposed, which are: unidirectional ‘studied’ following; ‘reciprocal’ following, when interaction between the user and the Tweeter only occurs online; and fully fledged friendship, when online relations are supplemented by offline meetings. The visibility of users via their Tweets creates information that others can use to evaluate character in what might be considered a phase of pre-friendship screening, and that this also generates trust and solidarity prior to an offline meeting. Perceived similarity between the user and the Tweeter was contributory to an assessment of their worth as a potential friend. Geographic proximity and ‘transferable trust’ were also factors that helped offline friendship to develop. Ultimately, Twitter was an important tool for sociality, and provided a wider source of potential friends than was available offline.