In rapid succession leftwing parties have been elected to government in some of the most important countries in the Latin American region. I challenge the view that there are two distinct variants of the leftone populist, the other social democraticand argue that variation on the left reflects the diverse conditions under which these forces emerge and evolve. I outline common features shared by the left in Latin America; suggest how the concept of populism and analysis of social movements can help explain this variation; and show how the left's commitment to egalitarianism, balancing markets, and, in some cases, its appeals to the constituent power of the people enabled it to benefit from disillusionment with the results of neoliberalism, the poor performance of democratic governments in Latin America, and the evolving international context.