This article examines the evolution of transnational Zapatista solidarity networks. Although scholars have described an emerging “mutuality” between the Zapatista movement and its allies at the level of international framing, this article considers how the Zapatistas forged this mutuality on the ground, through active redefinition of alliances with Northern supporters. It argues that the Zapatistas delimited who was included in their solidarity networks, set new terms for partnerships, and redefined legitimacy in their transnational alliances. In so doing, they asserted their autonomy from donors. They also fostered discourses and practices of mutual solidarity and Southern leadership, shifting the balance of power between North and South. The case both illuminates the possibilities for Southern movements to challenge Northern control from within and suggests potential pitfalls of doing so; by defying Northern NGOs' influence, the Zapatistas may have risked their long-term viability.