The evidence-based policy movement promotes the use of empirical evidence to inform policy decision-making. While several social science disciplines are undergoing a “credibility revolution” focused on openness and replication, policy analysis has yet to systematically embrace transparency and reproducibility. We argue that policy analysis should adopt the open research practices increasingly espoused in related disciplines to advance the credibility of evidence-based policymaking. We first discuss the importance of evidence-based policy in an era of increasing disagreement about facts, analysis, and expertise. We present a novel framework for “open” policy analysis (OPA) and how to achieve it, focusing on examples of recent policy analyses that have incorporated open research practices such as transparent reporting, open data, and code sharing. We conclude with recommendations on how key stakeholders in evidence-based policy can make OPA the norm and thus safeguard trust in using empirical evidence to inform important public policy decisions.