This research utilises a comprehensive survey to ascertain the level of social networking site personal information disclosure by members at the time of joining the membership and their subsequent postings to the sites. Areas examined are the type of information they reveal, their level of knowledge and awareness regarding how their information is protected by SNSs and the awareness of risks that over-sharing may pose. Additionally, this research studies the effect of gender, age, education, and level of privacy concern on the amount and kind of personal information disclosure and privacy settings applied. A social experiment was then run for 3 months that tested SNSs users’ reaction to a profile access request by a stranger. The research focused on four different social networks: Facebook, Twitter, Instagram,and Snapchat. The results of the survey and experiment found that there is a significant amount of personal information disclosure, but that the level differs between social networks. It is reveals that gender, age, and education have significant influences on information disclosure and user’s privacy settings and that on most sites over 50% of friend requests were readily accepted. These results are a selection from a comprehensive study of some of the more revealing facts about SNS user ship covering 3 months of data collection and almost 500 responses.