Scholars and policymakers generally agree that global performance assessments (GPAs) can influence the policy priorities and actions of public sector decision-makers. However, there is little systematic evidence about the conditions under which GPAs — and performance assessments, more generally — instigate changes in state behavior. There is also a lack of understanding about the causal mechanisms through which GPAs and other types of performance assessments facilitate policy changes. We seek to close this evidence gap by leveraging a survey of 1,788 host government officials that provides comparative data on the agenda-setting influence and reform design influence of more than 100 government performance assessments. We argue that GPAs function as signaling devices that provide credibility assurances to foreign investors and donors. However, the net benefits of credibility signaling to these external actors must be sufficiently large and certain for policymakers in assessed countries to recalibrate their domestic reform priorities and efforts. We posit that this condition is met when the supplier of a cross-country performance assessment allows assessed governments to participate in the assessment process. Using a multilevel linear model to account for the hierarchical structure of our survey data, we find evidence that performance assessments yield greater policy influence when they make an explicit comparison of government performance across countries and allow assessed governments to participate in the assessment process. This finding is robust to a variety of tests, including country-fixed and respondent-fixed effects.