Why do some individuals endorse public policies aimed at reducing income inequality while others oppose them? Why is there widespread support for such policies in certain countries, but not in others? This dissertation advances scholarship toward a general theory of support for redistribution by analyzing variation in redistributive attitudes within and across two developing democracies, Argentina and Peru. Support for redistribution is higher in the former country. It examines existing theories based on interests and group identity, explanations whose predictions have been almost exclusively evaluated in the context of advanced industrial democracies. It also introduces and assesses a belief-based explanation that focuses on inequality frames, simplified mental models of the issue of inequality comprised of individuals’ beliefs about the causes of economic outcomes, about the extent to which society provides equal opportunities, and about the nature of wealth accumulation. This dissertation argues that these theories are complementary and identifies the contextual factors that condition the extent to which the considerations emphasized by these accounts inform redistributive attitudes. Interests and group identity are salient in contexts where individuals have access to material and informational resources that make them more cognizant of their position along economic and ethnic cleavages. In contrast, inequality frames inform redistributive attitudes regardless of context because of their inside-the-head nature. This study shows that the relative dominance of redistributive beliefs in Argentina and self-reliance beliefs in Peru help explain why support for redistribution is higher in the former country. Finally, this dissertation develops a politico-historical explanation for why and how these frames became relatively dominant. This account argues that individuals’ inequality frames are relatively stable during times of normal politics, but malleable during certain critical political junctures brought about by major events like mass political incorporation or economic crises. During such times, individuals are particularly receptive to elite cues and messages that are transmitted not only via rhetoric but also via public policies. Redistributive beliefs become dominant wherever political actors whose discourse features elements consistent with the redistributive frame are able to implement successful comprehensive social policies. The self-reliance frame becomes dominant in countries where this combination of rhetoric and policies does not take place during a critical juncture. / text