Malicious actors use social media to advance destructive agendas, including political extremism, racial hatred, and election disinformation. Armed groups use these platforms to recruit and radicalize Canadians and crowdsource funding. Meanwhile, right-wing extremists use social media to disseminate disinformation at a scale never before seen, transforming political discourse and undermining democracy. Political and military battles are now fought as much on social media platforms as on the frontlines. Yet, the extent and impact of malicious actors' disinformation and radicalization efforts on social media remain poorly understood. Social media platforms do far less to combat these problems than is commonly assumed. At the same time, social media data holds the potential to provide an unprecedented and expansive real-time record of online and real-world events and their impact on communities and individuals. For instance, social media has been used as source of evidence in many high-profile criminal investigations, such as the shooting down of the Malaysian Airlines MH17 flight over Ukraine in 2014 by Russian military. That investigation, like many others, followed the incipient science of Open Source Intelligence, whereby experts and volunteers from the public analyze text, audio, and video posted online to identify key actors and events underlying the conflict or investigation.