An important consideration in judging the blameworthiness (or praiseworthiness) of an action is whether the agent had sufficient control over it. In three experiments, we investigated judgments of moral blame and praise elicited when individuals were presented with vignettes describing actions that were performed either carefully and deliberately or impulsively and uncontrollably. Experiment 1 uncovered an asymmetry between judgments of positive versus negative actions--negative impulsive actions elicited a discounting of moral blame, but positive impulsive actions did not elicit a discounting of moral praise. Experiments 2 and 3 showed that this asymmetry arises because individuals judge agents on the basis of their metadesires (the degree to which the agents embrace or reject the impulses leading to their actions). Individuals assume that an agent would embrace an uncontrollable positive impulse, and reject an uncontrollable negative impulse.