Why do political parties from former dictatorships crop up in many new democracies? What do the trajectories of these authoritarian successor parties (ASPs) under democracy look like? Why do some become permanent electoral actors under democracy while others obsolesce or collapse outright? This dissertation roots ASPs’ fates in the collective action of former authoritarian elite actors. Professional politicians, military officers, and economic elites from former dictatorships often retain access to critical resources under democracy that, when channeled toward an ASP, promote its capacity to weather the sudden and dramatic ups and downs that often characterize electoral competition in new democracies. But collective action by these elites is never assured, since individual elites often possess strong incentives during democratic transition to abandon their elite allies and instead pursue narrowly self-interested strategies of self-preservation. The question then becomes: When will a broad set of authoritarian-era elites act collectively to sustain an ASP under democracy? I argue that when making decisions over collective action and defection, authoritarian-era elites scrutinize the severity of threats to their core interests under democracy as well as the reliability of their fellow elites. In terms of the former, elites are more likely to coalesce within an ASP when threats in the form of transitional justice, erosions of de jure protections, and widespread demand for economic redistribution generate a perceived need for organized political protection under democracy. In terms of the latter, elite coalescence becomes more likely when a nascent ASP quickly signals its reliability as a political ally to authoritarian-era elites by staunchly defending the policies, projects, and historical justifications of the former dictatorship. I assess my argument using mixed methods. First, I leverage an original dataset on all Latin American ASPs from 1900 to 2015 to assess a key implication of my argument: In particular, if ASPs’ survival and success are largely rooted in their staunch defense of narrow elite interests under democracy, then the overall quality of democracy should suffer whenever ASPs crop up and exert their influence. Using regression analysis, I find systematic evidence of such a linkage: ASPs’ influence and access to governmental power under democracy is negatively linked to a host of high- and mid-level indicators that tap democratic quality. Critically, this linkage is robust to a range of controls as well as prominent alternative explanations, including ASPs’ antecedent organizational capacity, the persistence of authoritarian-era institutions under democracy, authoritarian regime type-specific legacies, and opposition party weakness. I further assess my argument using detailed analyses of ASPs in contemporary Chile and Peru. My analyses draw on original archival data as well as data from roughly 100 in-depth interviews with former authoritarian elites and contemporary ASP leaders. In Chile, I examine puzzling divergence in the post-transition trajectories of the Independent Democratic Union (UDI) and National Renewal (RN), both of which emerged from the military dictatorship headed by General Augusto Pinochet. In Peru, I examine the surprising revival and consolidation of Fujimorismo, an ASP that emerged from the personalist dictatorship of Alberto Fujimori. In both countries, I show how ASPs’ survival and eventual success derived from the support of broad sets of authoritarian-era elite actors. However, I additionally show how such support was neither immediate nor automatic. Rather, elites only belatedly flocked to ASPs under democracy in response to successive and growing threats to their core interests, and they did so only after ASPs’ early behavior under democracy had persuaded them of ASPs’ reliability as political allies.