Despite the prevalence of dating websites and hookup applications, mass communication scholars have largely ignored news coverage of sex in the digital age. Research about online sexuality has built on early theories of cyber identity, in which the Internet was conceptualized as a great emancipator. Online, it was argued, people could explore “disembodied” sexualities with little interference from offline reality. This dissertation builds a research line that investigates journalistic discourse about online sexuality using more than a decade of coverage of Craigslist sex forums as a case study. It also examines user activity on Craigslist sex forums, testing dominant theories of online identity. For journalists, Internet-mediated sexuality represents a compound moral threat. Since 2003, national U.S. newspapers have consistently identified the classified ads website Craigslist as a hotbed for sexual deviants — people whose sexual interests mainstream culture deems immoral or even illegal. Newspaper journalists call on police and government sources to frame Craigslist users as prostitutes, violent criminals, and cheating politicians. By relying on elite sources, news media surveil social deviance for the public. This is an outcome of normative reporting practices. Representational scholars have argued that media made by marginalized groups will provide more nuanced narratives than the mainstream press. But in stories about Craigslist sex forums, alternative media reproduce stigma about online sexuality. Popular LGBTQ and feminist online magazines describe Craigslist sex forums as catalysts for illegal and immoral activity. They sometimes privilege sex workers’ voices and cover the experiences of sexual minorities, but they contribute to the same deviance-defining discourse about Craigslist sex forums as does the mainstream press. Media across the ideological spectrum police social deviance and reinforce cultural norms — online and off. Mass media surveillance of online sexuality encourages people to surveil their own behavior online. Ads on Craigslist sex forums reflect dominant cultural norms about sex despite posters’ attempts to explore their “unusual” fantasies. The Craigslist Casual Encounters forum provides a productive outlet for people to fantasize about kink, non-monogamy, race, and sexuality. But it also reflects the politics of its white male user base. Sexism, homophobia, and gendered logics saturate the forums. Offline stigmas about sexuality bleed into online sexual expression. This dissertation theorizes the role of normalizing judgment in determining media representations of online sexuality. It offers perspectives from journalism sociology and cultural studies to help explain why media paint Craigslist sex forums as spaces that foster illegal and immoral sex. The dissertation concludes that online sexuality must be added to definitions of deviance in news. It problematizes theories of representations of sexuality by alternative media, and it demonstrates that online sexuality is deeply intertwined with offline identity.