What factors determine whether a person's beliefs are epistemically rational? Many traditional accounts contend that those factors lie in the beliefs themselves. For example, a belief can fit with one's evidence, it can originate in reliable (or otherwise virtuous) processes, or it can cohere with other beliefs (some of which may be self-justifying). In this provocative book, Franz-Peter Griesmaier presents a new picture of epistemic rationality, emphasizing the role of the agent rather than the belief. The rationality of an agent's beliefs ultimately depends on her epistemic sophistication, which is manifest in the stringency of her standards, in the skill she has in accessing and evaluating evidence, and in the wisdom she displays in choosing contextually appropriate standards. To be epistemically rational means, in this view, that one has discharged one's epistemic duties by using the contextually proper standards for finding and evaluating the available evidence during the process of belief formation. In the course of defending this view, Griesmaier discusses a wide variety of topics from the perspective of a unifying framework. These topics include the possibility of lucky justification, the importance of error avoidance, the problem of simplicity, various forms of evidentialism, doxastic voluntarism, epistemic deontologism, the question of belief's aim, contextualism, and the connections between his account and formal models of justification and knowledge, such as epistemic and justification logics.