The major element missing from Latin American politics in recent decades has been, with rare exceptions, the traditional workers' movement, beaten down by flexibilization, subcontracting, and other neoliberal measures.… The fall of the Berlin Wall and the defeat of Soviet socialism left the parties and social organizations of the left inspired by that model seriously weakened. At the same time, trade unions were hit hard by the weakening of the working class, part of the larger social fragmentation produced by neoliberalism. In that context, it was new social movements, and not the traditional parties and social organizations of the left, that rose to the forefront of the struggle against neoliberalism, in forms that varied widely from one country to another.… The situation in the 1980s and '90s in Latin America was comparable in some respects to the experience of pre-revolutionary Russia in the early twentieth century.… [M]any of the region's peoples said "enough" and started mobilizing, first in defensive resistance, then passing to the offensive. As a result, presidential candidates of the left or center-left began to triumph, only to face the following alternative: either embrace the neoliberal model, or advance an alternative project motivated by a logic of solidarity and human development.… [Consequently,] a major debate has emerged over the role that new social movements should adopt in relation to the progressive governments that have inspired hope in many Latin American nations.<p class="mrlink"><p class="mrpurchaselink"><a href="http://monthlyreview.org/index/volume-67-number-8" title="Vol. 67, No. 8: January 2016" target="_self">Click here to purchase a PDF version of this article at the <em>Monthly Review</em> website.</a></p>