In considering issue expertise in policymaking, we unpack differences in the supply and types of expertise with attention to the presumed privileged role of the bureaucracy. Our empirical investigation is based on witness testimonies of congressional hearings for a policy area involving various forms of expertise – critical infrastructure protection policymaking. Three sets of findings stand out. One set substantiates the role of the bureaucracy as an important information conduit while also showing it is not a primary source of issue expertise. A second set shows how differences in issue maturity and salience affect the demand for and supply of expertise. A third set illustrates the influence of a small cadre of hyper-expertise in drawing attention to problems and solutions across different venues. These findings challenge the conventional view of the bureaucracy in policymaking while expanding the understanding of different sources of information and types of issue expertise in policymaking.