Social media has given rise to a number of detrimental issues that society has yet to fully grapple with, including interpersonal privacy violations and radicalization. Interpersonal privacy violations occur when users share sensitive photos of other people and others’ personal information. Our research seeks to address this issue by identifying factors that drive social media sharing decisions, groups disproportionately affected by privacy violations, and interventions to prevent interpersonal privacy violations. Radicalization is a second major issue, where people adopt more extreme beliefs, attitudes, and behaviors overtime due to their social media interactions. Our research evaluates the process of online radicalization and applies new quantitative tools to detect, predict, and intervene to prevent the spread of extremism.