The author demonstrates that parental management practices can explain variation in a child’s self-control only if rational judgment is not the underlying cause of behavior, which contradicts the assertion of Gottfredson and Hirschi. This leads to the question, if rational judgment is not the ultimate determinant of behavior, what is? The author proposes the pleasure/pain principle. This principle asserts that people care about the consequences of their behavior, whether the consequences are long-term or short-term, as a result of the pleasure or pain experienced at the time the decision is made. This “hedonism of the moment” is inconsistent with Gottfredson and Hirschi’s contention that rational judgment ultimately determines behavior. The issue in behavior is not whether it meets the actor’s test of rationality, but rather whether the actor’s decision is linked to an immediate increase in pleasure or decrease in pain as a result of the chosen behavior. If self-control is exercised in behavioral decisionmaking, it is because the particular individual experiences more pleasure or less pain as a result of using self-control to refrain from impulsive guilt-producing or shame-producing tempting behavior. Although acting under the principle of “hedonism of the moment” maybe considered “rational,” rationality is not the ultimate basis for the behavior. “Hedonism of the moment” is a restatement of Hume’s statement that “reason is the slave of the passions.” The article concludes with a review of recent empirical evidence that confirms the principle of hedonism of the moment as the basis for behavior. 7 notes and 40 references