This paper provides a political-economic analysis of policy evaluation. We focus on Randomized Controlled Trials (RCTs) as a subset of policy evaluations and argue that they are used instrumentally by decision-makers in order to improve perceptions of reforms and help secure policy legacy. We theorize that this ’credibility premium’ is more valuable for incumbents in politically polarized societies, which we empirically examine using two methods. First, we provide a series of vignettes of prominent randomized evaluations embedded by governments in policy roll-outs and a detailed case study of the Liberian government’s decision to commission a third-party RCT evaluation of a proposed primary school privatization reform. Second, we have compiled a unique cross-country panel data set on RCTs in development policy since 1996, with which we demonstrate that RCTs are more likely to occur in polarized societies, and that the effect is amplified by the degree of political competition.