Executive Summary YouTube, the most popular social media platform in the United States, dominates user-generated long-form video-sharing around the world. Like other major platforms, it has a dual nature: It provides two billion users access to news, entertainment, and do-it-yourself videos, but it also serves as a venue for political disinformation, public health myths, and incitement of violence. “ YouTube has been less scrutinized than other platforms by social scientists, politicians, and civil society groups, including ours. This report seeks to address this knowledge deficit. ” YouTube’s role in Russia illustrates this duality. Since Russia launched its invasion of Ukraine in February 2022, YouTube has offered ordinary Russians factual information about the war, even as the Kremlin has blocked or restricted other Western-based social media platforms and pressured foreign journalists in the country to silence themselves. But for years before the brutal incursion, YouTube served as a megaphone for Vladimir Putin’s disinformation about Ukraine and its relations with the West. Despite its heft and influence, less is known about YouTube than other major social media sites. A subsidiary of Google, YouTube has been less scrutinized by social scientists, politicians, and civil society groups, including ours. As a result, we know less about YouTube’s business practices and the effects they have on the societies in which it operates. This report seeks to address this knowledge deficit. In Part 2, we examine YouTube’s role as the internet’s vast video library, one which has contributed to the spread of misinformation and other harmful content. In 2019, for example, YouTube reacted to complaints that its recommendations were pushing impressionable users toward extremist right-wing views. The company made a series of changes to its algorithms, resulting in a decline in recommendations of conspiratorial and false content. But recommendations are not the only way that people find videos on YouTube. A troubling amount of extremist content remains available for users who search for it. Moreover, YouTube’s extensive program for sharing advertising revenue with popular creators means that purveyors of misinformation can make a living while amplifying the grievances and resentments that foment partisan hatred, particularly on the political right. In Part 3, we turn our attention to YouTube’s role in countries outside of the U.S., where more than 80% of the platform’s traffic originates and where a profusion of languages, ethnic tensions, and cultural variations make the company’s challenges more complicated than in its home market. Organized misogynists in South Korea, far-right ideologues in Brazil, anti-Muslim Hindu nationalists, and supporters of Myanmar’s oppressive military regime have all exploited YouTube’s extraordinary reach to spread pernicious messages and rally likeminded users. HOW YOUTUBE SPREADS HARMFUL CONTENT – AND WHAT CAN BE DONE ABOUT IT 1