Policy discourses on the online safety and security of girls participating in social media are often focused on teaching strategies to secure personal information and increase digital literacy. Moreover, these discussions typically leave out what girls and young women view as threats to their security and online safety, and the ways they already manage these threats through the use of risk reducing behaviours (Regan & Steeves, 2010). This paper will present the views of girls and young women aged 15-22 regarding the security issues they encounter while participating in online social media, and how they manage themselves accordingly. Specifically, girls and young women noted that the technical architecture of social media sites impacts their feelings of safety and how they behave online. In particular, how a website was structured and whether it included aspects that girls and young woman viewed as indicators of security (e.g., professionalism, expertise, site access, control of personal content, and consistency) influenced how they would participate on the site. Consequently, in response to ‘risky’ sites, girls and young woman managed their privacy and security by employing risk reducing strategies such as the use of lateral surveillance, responsiblization techniques (e.g., restricting privacy settings and blocking, deleting, and minimizing), and resistance (e.g., using fake names). Therefore, effective policy discourses should also consider the technical architecture of social media sites and how the online infrastructure can be shaped to improve the security of girls and young woman and enhance their online participation in positive ways.