This thesis focuses on the breakdown of authoritarian regimes, developing an original account of the way in which non-democratic regimes can be successfully challenged by mass-based uprisings. Authoritarian regimes, in fact, are not only defeated by elite negotiations or by a partial political liberalization initiated by the ruling coalition at a time when collective protests have already delegitimized the dominant coalition. As happened in Tunisia and Egypt, authoritarian regimes can also break down without pacts, negotiations, and compromises. Although this is a much less frequent path, autocracies are also defeated by mass-based uprisings in which the emergence of a cross-class and cross-ideological coalition throughout (almost) the whole country imposes a regime change. In Algeria, on the contrary, it was exactly the non-emergence of a broad opposition coalition that explained the authoritarian stability.