A long tradition in Western thought has enshrined reasoning as the surest way to reach a sound decision, although the opposing point of view, that sees intuition as a superior basis of many decisions, has had many advocates throughout history. But how do people actually balance intuition and reason when making decisions? I report nine studies that indicate that people use features of the choice (Studies 1-3) or features of their mental states (Studies 4-8) as cues when deciding whether to follow intuition or reason. That is, features of the choice and the chooser's mental state are matched to the characteristics of rational or intuitive processing to determine whether to follow intuition or the dictates of a more deliberate, reasoned analysis. Choices that are seen as objectively evaluable (Study 1), complex (Studies 2a and 2b), or important (Study 3) elicit a preference for choosing rationally, as do mental states of carefulness and caution (Studies 4, 5, and 6). Conversely, mental states involving vividly pictured choices (Study 7) or persistent intuitions (Study 8) elicit an increased preference for choosing intuitively.