Researchers across varied disciplines have begun to explore social media as a new delta of communication; however, few are taking a hard look at social media as it relates to crime. Sites such as Twitter and Facebook increasingly are being used by law enforcement as tools for engaging in criminal investigation, improving public relations, and increasing public awareness. Similarly, persons engaging in crime increasingly employ such sites in novel and unique ways to network, exchange information, and execute and record criminal activities. A survey of research in fields ranging from computer science to sociology to communications demonstrates that both quantitative and qualitative research on and about social media have the capacity greatly to advance contemporary understanding of social organization and protest, crime and criminal behavior, and law and social control. For example, Facebook and Twitter have become key sources for gaining insights into criminal behaviors, such as gang activity, as well as on-the-ground data regarding significant events, such as the Occupy Wall Street, Arab Spring, the Black Lives matter movements, and elections of public figures. Other applications, such as Snapchat and Kik, provide the opportunity for immediate transmission of content and a new source of evidence to be used in criminal prosecutions. Studying social media from a criminal justice perspective, however, is a complex endeavor. While the Internet offers seemingly limitless opportunities for social organizing and networked engagement, the forum bears as much capacity for exclusion as it does for liberation. The growth of new social ills or crimes, such as “doxing,” “phishing,” and “revenge pornography,” for example, highlight that the confluence of immediacy of communication, perceived anonymity, and lack of moderation often renders the online environment threatening for perceived outsiders, particularly young women. On the other hand, as incidents, such as online threats against gamer Zoe Quinn and blogger Anita Sarkeesian, have come to light, online content is increasingly monitored, regulated, and controlled by its corporate ownership, who generally reveal little about how information is sorted, prioritized, and disseminated. As a researcher, one must be mindful that data, particularly qualitative data, collected from social media sites may not be random, representative, or generalizable. In addition, attendant to studying the Internet are unique ethical and privacy concerns not present in non-virtual fora. Many describe the Internet as a public sphere, and law enforcement often treats the online environment as a location in which Fourth Amendment privacy protections can be less rigorously observed. For researchers, however, it is essential to carefully consider whether the study of online discourse is archival or is human subjects research, and in the case of the latter, whether and how consent might be obtained. It is also important that researchers are attentive to the particular characteristics of the online site or sites they choose to examine, as the mission, rules, and practices of each site vary dramatically.