Curiosity refers to a demand for information that has no instrumental benefit. Because of its critical role in development and in the regulation of learning, curiosity has long fascinated psychologists. However, it has been difficult to study curiosity from the perspective of the single neuron or the circuit – that is, at the systems level. Recent advances; however, have made doing so more feasible. These include theoretical advances in defining curiosity in animal models, the development of tasks that manipulate curiosity, and the preliminary identification of circuits responsible for curiosity-motivated learning. Taken together, resulting scholarship demonstrates the key roles of executive control, reward, and learning circuits in driving curiosity and has helped us to understand how curiosity relates to information-seeking more broadly. This work has implications for mechanisms of reward-based decisions. Here we summarize these results and highlight important remaining questions for the future of curiosity studies.