How does the use of evidence by policy makers differ for issues that are highly politicized compared to those that are not? Does the answer depend on whether the venue for policy making is the legislative or the executive branch? We explore these dynamics through state-level case studies of two different types of issues: what type of health insurance exchange to establish as part of the implementation of the Affordable Care Act (Idaho and Mississippi), and how to reduce infant mortality (Florida and Georgia). We highlight four sets of issues critical to understanding the use of evidence: (1) characteristics of a policy, (2) characteristics of the policy makers, (3) characteristics of the producers and disseminators of evidence, and (4) different ways evidence can be used. Barriers for academics to contribute directly to policymaking change for politicized issues, particularly in the legislative branch. Under these circumstances, intermediary groups such as ideological think tanks become a trusted source of information. Policy makers themselves are a key source of evidence on less politicized issues in the executive branch. Academics wanting to inform politicized policy making need to appreciate and be comfortable with the blurry line between instrumental and rhetorical uses of evidence.