A key factor underpinning a state’s capacity to respond to cyber security policy challenges is the quality of evidence that supports decision making. As part of this process, policy advisers, essentially a diverse group that includes everyone from civil servants to elected policy makers, are required to assess evidence from a mix of sources. In time-critical scenarios where relevant expertise is limited or not available, assessing threats, risk and proportionate response based on official briefings, academic sources and industry threat reports can be very challenging. This chapter presents a model for assessing the quality of evidence used in policymaking. The utility of the model is illustrated using a sample of evidence sources and it is demonstrated how different attributes may be used for comparing evidence quality. The ultimate goal is to help resolve potential conflicts and weigh findings and opinions in a systematic manner.