A growing body of work suggests that authoritarian regimes can enhance their external legitimacy by undertaking reform—from democratic or “pseudodemocratic” institutional changes at the domestic level to participation in international efforts to mitigate climate change. Yet the shared theoretical logic underlying this work has received surprisingly little empirical attention. This research contributes by offering findings from an iterative series of original survey experiments conducted over nationally representative samples of US citizens. Study 1 tested the foundational hypothesis—that reforms build external legitimacy—by adopting a simple independent groups design. Studies 2 and 3 subjected that hypothesis to harder tests via conjoint designs, and also evaluated extension hypotheses about when and in what sense “legitimacy” is gained. Across studies, the results consistently demonstrate that reforms (of a variety of types) do generate external legitimacy, offering both positive benefits as well as shielding benefits in keeping with theoretical arguments. The results also provide support for several new and previously undocumented findings concerning the role of reform type, type of legitimacy-derived gain, and the conditions under which such gains are more or less likely to accrue.