The ubiquity of streaming sites such as Pornhub has transformed the social role of sexually explicit content today. Online porn is no longer a shady corner of the internet; it is mainstream. Its production, commodification, and consumption on data-driven online platforms has changed – and is changing – our personal relationships, social and legal systems, and sexual norms. Online porn platforms are shaping sexual desires and practices in the same way that Google and Facebook have affected social relationships and the circulation of information: porn is now consumed on data-driven platforms with algorithms designed to engage the attention of users, encourage the production of user-generated videos, and filter content. Through frank examination of mainstream content with themes of incest, intoxication, and so-called consensual rough sex, issues that play out in life and in court, Elaine Craig shows how the platformization of mainstream pornography is shaping our sexual culture in real time. Mainstreaming Porn maps a complicated web of legal culture and legal actors, from corporate lawyers and platform content regulation to the criminal, civil, and administrative contexts in which porn companies operate and the legal interpretation of sexual assault defences. All have profound implications for the promotion and protection of everyone’s sexual integrity, and especially that of women and girls. Mainstreaming Porn is an unflinching, carefully balanced perspective on a divisive topic. Without demonizing pornography or its consumption, Craig makes a powerful argument for applying legal mechanisms to corporate-owned online platforms while offering a sober evaluation of the limits of the law in governing pervasive cultural norms and social understandings of sexuality.