In this introduction to the special issue Contesting the Mainstream: Understanding Alternative News Media, we discuss how and to what extent alternative news media contribute to news diversity. We elaborate on the concept of diversity, the democratic role of media, and the normative implications of alternative media in the wider media sphere. Based on the articles published in this special issue, that offer new and revealing empirical insights into a wide range of alternative media sites and their practices, from Europe, Asia, the Middle East, North America, and Latin America, we argue that it becomes increasingly clear that awareness about normative positions within alternative media research is imperative. This is because an appreciation of the normative purpose of alternative media guides our ability to understand their role in society. The necessity for thinking through such positions is particularly exemplified by the most radical alternative media actors, and how they are debated and studied in different political systems.