This study builds a conceptual framework to guide empirical studies of learning in public policy. Learning in public policy is defined here as a process in which individuals apply new information and ideas to policy decisions. This topic is examined by adapting relevant concepts from studies of organizational learning to the context of public policy. Recent work in the organizational learning literature focuses on institutional structures, procedures, and customs (learning arrangements) that act to promote individual learning. Further work in the policy literature suggests that focusing events (incidents that focus public and political attention on a policy issue) can also shape learning in public policy. Combining insights from these two literatures, this study proposes that both learning arrangements and focusing events can play observable roles in shaping policy change over time. These concepts are developed and examined in the context of hazardous systems.