This book describes the results of a six-year ethnographic research project on Wikipedia. It explains how Wikipedia's theoretically ahierarchical system may increase Wikipedians’ perception of inequality in practice and how hierarchy is enacted through community elections. Although Wikipedia is sometimes portrayed as collaborative and peaceful, it often breaks into conflicts and disputes. The book describes how the gradual increase in editing participation determines its attractiveness, addictiveness, and, ultimately, its level of conflict. The seemingly chaotic organization of cooperation on Wikipedia is actually susceptible to tight control through observation of all behaviors, the participants’ structured discourse, and procedures. Nonetheless, organizational control, so strict in other aspects, is more lenient on Wikipedia than in other types of organizations in terms of credential checks, as a result of a transformation of interpersonal trust and of trust in procedures. The lack of recognition of real-world credentials and formal authority helps sustain the Wikipedia community, by both allowing for alternative authority-building patterns and negating the real-world knowledge structures. The book studies the internal composition of the Wikimedia movement and describes how it is influenced by increasing professionalization. Finally, it reviews the evolution of Jimmy Wales's leadership of Wikipedia and explains how open-collaboration communities require congruence in terms of their organizational leadership model (authoritative or egalitarian) and the exercise of leadership power (direct and interventionist or general and visionary).