This article considers the contribution of functional neuroimaging toward understanding the computational underpinnings of human decision making. We outline the main processes likely underlying the capacity to make simple choices and describe their associated neural substrates. Relevant processes include the ability to encode a representation of the expected value or utility associated with each option in a decision problem, to learn such expectations through experience, and to modify action selection in order to choose those actions leading to the greatest reward. We provide several examples of how functional neuroimaging data have helped to shape and inform theories of decision making over and above results available from traditional behavioral measures.